Challenging Outdated Practices: The Conflict Between Evidence and Habit in Lean Management


tl;dr: In this post, Mark explores the tension between traditional habits and current scientific evidence in Lean management practices. He delves into how old habits can persist, even when newer, evidence-based methods are available. Mark argues for a more rational approach to decision-making, urging professionals to rely on current evidence rather than outdated practices. The post offers insights into the complexities of change management and the challenges in adopting evidence-based practices.

If you missed yesterday's blog post and podcast with Dr. Rob Hackett from Australia, please check it out.

After meeting Rob and corresponding over the past few weeks about various patient safety issues, one topic that keeps coming up is the force of habit.

I find it really interesting when scientific facts and truth get superseded by new evidence. Science isn't supposed to be stubborn… it's OK to cast aside the old status quo when we learn something new (pay attention, “flat Earth” crowd).

There are a lot of these themes, also, in a book I've been reading, The Case Against Sugar, by Gary Taubes. Some of the established science about low-fat diets being good for us might not really be true.

As many dietary experts and the government have pushed low-fat diets since the 1970s, obesity has gone up dramatically. Maybe we have a more complicated systems issue, where some scientists are quite certain that eating sugar leads to our body converting it to… fat. When the makers of processed foods remove fat, then end up adding…. sugar, which then gets turned into…. fat.

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Some say it's more complicated than saying “a calorie is a calorie.” Maybe our body treats sugar different than fat.

Taubes writes, about science and progress:

History is critical to understanding science and how it progresses. In many scientific disciplines–physics, for example–the science is taught with the history attached. Students learn not only what is believed to be true and which conjectures have fallen by the wayside, but on the basis of what experiments and what evidence, and by whose authority and ingenuity.

The names of the physicists responsible for the advances in understanding–Newton, Einstein, Maxwell (for his equations of electromagnetism); Heisenberg, Planck, and Schrödinger, among others, for their work in understanding the quantum nature of the universe; and many more–are as well known as many historical figures in politics and other fields.

Medicine today, though, as with related fields such as nutrition, is taught mostly untethered from its history. Students are taught what to believe but not always the evidence on which these beliefs are based, and so oftentimes the beliefs cannot be questioned.

And medical students are not taught, as physics students typically are, to question everything that has not demonstrably survived the trial-by-fire process of rigorous, methodical testing.

Students of any science need to know why they are being asked to believe a particular idea, or why not, and on what grounds. Without the history of the idea, there's no way to tell and, by implication, no reason to ask.”

Taubes, Gary. The Case Against Sugar (p. 21). Knopf Doubleday Publishing Group. Kindle Edition.

Lean and Conjecture

Maybe the “Lean community” (a phrase I use without fully understanding what it means) should look at which “conjectures [about Lean] have fallen by the wayside, but on the basis of what experiments and what evidence, and by whose authority and ingenuity”?

I was at one point taught, and sort of believed, “You should always start with 5S.” Somebody might have tried to explain why. Some still say this. But, in my mind, that conjecture has proven to be untrue… absolutes like “always” or “never” are rarely true in a complicated world.

I saw the other day on LinkedIn how somebody was rigidly teaching their students to “always start with Value Stream Mapping,” and they stated a hope that if their students were given conflicting advice in the future, that they'd say, “But that's not what I was taught.”

“Because I was taught this way,” is not really the best reason to keep doing something anymore than saying, “The Standardized Work says to.” Lean is supposed to be more of a scientific, thinking process… and less about dogma… or at least that's what I was taught. ;-)

The Bike Log Book

Back to the medical realm, Rob shared this article with a funny story:

“A few years ago, the Dean of the School of Business at the University of Leicester, Dr Zoe Radnor, tried to understand the reasons for the “bicycle book” that she discovered at an English hospital she was studying. All staff who arrived at work by bicycle routinely signed a register book at the front door. Hundreds of these registers, once full, had been collected and stored for decades in clearly marked boxes. “Why?” Professor Radnor asked. No one knew.

The answer took some sleuthing. The first books dated from World War II–when rationing of fuel was the rule of the day, and when any staff who commuted by bicycle thereby earned extra food ration credits for saving on gas.

Now, three-quarters of a century later, the bicycle book process remained alive and well, embedded in the organization's brainstem, not its cortex. It was pure waste.

That's certainly a funny, illustrative story. But, at least nobody was harmed by the practice… it just wasted time, money, and space.

Habits, Ritual, and Evidence in the Operating Room Area

Getting into the clinical realm, one thing that Rob shared with me was the common (and old) practice of people wearing shoe covers into the operating room.

As he wrote:

“…we still wear shoe covers in theatre despite not having used flammable anaesthetic gases since the 1950s (before my time).”

He shared a part of an article that discusses this:

“Shoe covers remained part of the acoutremonts of the surgeon… current evidence suggestes that the use of shoe covers actually may enhance the transmission of bacteria from the soles of one's shoes to the surgical wound… especially if one does not wash one's hands after putting on the shoe covers.”

So, again, if the shoe covers with the anti-static strap on the bottom aren't needed, the shoe covers must be needed for infection control then, right? Nope.

Some people, it seems, use disposable paper toilet seat covers. But, that habit doesn't prevent the transmission of germs, as this article discusses. The paper says:

“Seat covers do not stop germs, they said, and you're not likely to catch an infection from a toilet, anyway.”

How many people have this habit with the belief that it's helpful?

The bigger germ-transmission risk is the “plume” that comes from flushing a toilet that doesn't have a lid to close over it. Closing the lid, when there is one, is probably a better habit.

Here is an article that also talks about shoe covers (PDF):

Behaviours and rituals in the operating theatre

It says:

“Rituals are described as any action performed according to custom, without understanding the reasons why it is being practised.”

Is your practice of Lean based on science, reasons, or ritual?

Theatre footwear

The floor surface of the operating theatre should be kept clean but the effect this has on infection rates remains uncertain. Studies of bacterial contamination of the operating theatre corridor floors indicate that a change of footwear should occur as far from the operating theatre as possible. Well-fitting footwear with impervious soles should be worn and regularly cleaned to remove splashes of blood and body fluid.

All footwear should be cleaned after every use, and procedures should be in place to ensure that this is undertaken at the end of every session. Humphreys et al. illustrated that the use of plastic overshoes led to a significant increase in floor colony counts rather than a decrease. Carter also showed that hands became contaminated when overshoes were put on or removed.

Recommendation: category 3
Special footwear should be worn in the operating department and regularly cleaned. The practice of
wearing plastic overshoes should cease

The last time I was in an operating room setting a lot, I was taught their standardized work. This included putting on shoe covers. I was taught to take off the shoe covers and to throw them away when leaving the surgical area.

But, I saw many, if not MOST, staff wearing the covers out and about… not stopping to replace them when coming back into the surgical area. Ugh. They aren't magical germ repellents. This is like the one time I saw a Subway employee cough onto their gloves… and then was about to resume making the sandwich. I spoke up and asked him to change gloves.

Maybe the operating rooms should be more like most any building in Japan, where you remove your outside footwear and put on slippers or plastic shoes to wear indoors. Are operating rooms managed by habit or science?

“Redfern describes a study in which only 12% of practitioners based infection control (IC) practice in the operating theatre on evidence.”

There are other practices that seem to be at least somewhat debunked in the article. Recommendations for new practice or further research include:

  • Not having patients remove clothing for procedures like cataract removal – “the most illogical of rituals” (Spock would like that)
  • Not making patients wear a hat to cover their hair during surgery
  • No longer having patients remove rings or jewellery unless “they are in the operative or anasethetic field”
  • Stop shaving parts of the patient other than the “area to be incised” (and depilatory cream is better than razors or clippers)
  • Don't have patients take a pre-op chlorhexidine shower
  • There's no need to do more than a 2-min hand wash… and alcohol hand rub is an acceptable alternative to repeated washing
  • “Alcohol solutions are preferred to aqueous solutions for skin preparation but it is important to allow the alcohol to dry after application and before the use of electrocautery.” And, use single-use bottles to prevent contamination.
  • “… masks should be worn for the protection of the wearer, however there is insignificant evidence to support the continued wearing of masks to prevent wound infection” (with the exception of “prosthetic implant operations”).

Back to Rob's question of names on surgical caps (and the related controversy over cloth caps versus disposable bouffant caps):

  • “There is no need for non-scrubbed staff members of the operating team to wear disposable headgear, however common sense dictates that hair should be kept clean and out of the way.”

That would have applied to me when I was around the operating rooms (being literally outside the rooms, not inside during surgery) but they had me wear a bouffant cap.

  • Wedding rings can be worn, “although surgeons may be advised to remove these” when “working with metal prostheses”
  • There's no need to put on a cover jacket over surgical attire when leaving the theatre area
  • “The practice of wearing plastic overshoes should cease”
  • Adhesive mats on the floor (intended to reduce infections) may actually “become a reservoir and source of contamination” and shouldn't be used

It's an exhaustive study. For those of you in hospitals every day, I wonder which practices are followed… how much evidence-based care is there and how much of it is habit?

How would you answer those questions about your Lean practices?

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Mark Graban
Mark Graban is an internationally-recognized consultant, author, and professional speaker, and podcaster with experience in healthcare, manufacturing, and startups. Mark's new book is The Mistakes That Make Us: Cultivating a Culture of Learning and Innovation. He is also the author of Measures of Success: React Less, Lead Better, Improve More, the Shingo Award-winning books Lean Hospitals and Healthcare Kaizen, and the anthology Practicing Lean. Mark is also a Senior Advisor to the technology company KaiNexus.


  1. This reminds me of the famous pot roast story where a mom teaches her child to cut off the ends of a pot roast before they cook it. When the child asks why they do that the mom replied she learned it from her mom. The child called the grandma and asked why she cut the ends off and she replied it was because her stove was too narrow and had to cut it to make it fit. The point is we often have standards and beliefs based on old conditions that no longer exist! In other words, the science is outdated! Great post!!


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