I was running errands around Boston last Saturday, preparing for our move back to Texas (as my wife finishes her 12 month grad school program).
In the course of these errands, I had some thoughts about Lean or related to it (or just fun thoughts, maybe), including:
- Why 100% utilization isn't possible or optimal
- Visual controls with moving tape
- Good “flow” from a store to a dental practice office
100% Utilization Doesn't Work
Being in Boston for the year, we didn't bring a car with us from Texas. We've been taking the T, walking, and taking cabs. One other service I've been a big fan of is ZipCar– a car sharing service.
Looking back to a book like Lean Solutions, ZipCar might be considered “lean” in the sense that you're buying mobility (customer need) rather than buying a car. You're paying for a service, by the hour, instead of owning an asset. ZipCar is incredibly convenient and I recommend it highly.
Yesterday was the first I've reserved a ZipCar when it was booked right up until my time. I had the car from 2 pm to 3:30 and it was booked immediately before and after my time slot. I was waiting for my car at 1:59, so I was starting to call ZipCar to find out what happens if the car isn't available. And sure enough, there was the driver pulling in at 2:00 on the dot. So, no problem.
Here's an afternoon where that ZipCar was going to be basically 100% utilized (or 100% rented). 100% utilization, in any system, causes dysfunctions and waiting times, however. I'd assume ZipCar's financial model and business plan isn't built on 100% utilization, or they'd go out of business. For one, 100% utilization wouldn't be possible, so there would be a financial shortfall. Secondly, with 100% utilization, customers would find it difficult to schedule cars, so they'd turn to an alternative and not get into the habit of using ZipCar.
Too many organizations, using non-Lean batch thinking, aim for 100% utilization. As we learn from the amazing textbook Factory Physics, 100% utilization (or anything close) leads to long customer waiting times. Depending on the variation in the system, the waiting times explode beyond 70% or 80% utilization. A system designed around 100% utilization isn't going to work well, it isn't going to flow.
Many factories try to plan for 100% utilization of machines. This often leads to long delivery times and lots of WIP inventory. Pressure to run 100% might also lead to the “Waste of Overproduction” if you keep a machine running to make stuff customers aren't buying. Now, if you have a very expensive piece of equipment, you'd be smart to pay attention to its utilization (not budgeting for 100% isn't an excuse to let utilization be too low).
Many hospitals have been in that same trap – they want 100% utilization of resources like:
- operating rooms
- MRI machines
The goal of 100% utilization leads to dysfunction and waiting time. Yes, we don't want the doctor to be idle anymore than ZipCar wants its vehicles to be idle, but you need some “slack capacity” in any system for things to flow (the book Slack: Getting Past Burnout, Busywork, and the Myth of Total Efficiency is a GREAT one on this topic).
To have a surgeon be 100% utilized, you end up with the practice of patients all being brought in at 6 AM to wait (and wait and wait) until their surgery begins (which might be in the afternoon). With this intentional queuing of patients, the surgeon will keep busy even if a patient was a no-show. We need to look for the proper balance between making sure the doctor's time (or MRI machine's) isn't wasted (not too much idle) time, but we can't expect or budget for 100% without lots of other dysfunctions.
I'm going to do a podcast soon with Dr. Kate Sylvester of the National Health Service in England. One of the things we are going to talk about is her campaign to teach people how harmful 100% efficiency goals are, because of the dysfunctions. So, more on that soon.
Since we've been in Boston only semi-permanently, we didn't move too much stuff. But, for anyone who has moved, you know how important it is to label boxes so you know where they go (which room) when you arrive.
Markers might work fine, but for those who want an extra level of moving visual management, the store sold this “Smart Tape” — you close up your boxes with this color coordinated tape that's labeled for different rooms. Helpful or overkill? It's in the eye of the mover.
One thing I noticed after bringing the boxes home was that U-Haul actually encourages you to re-use boxes multiple times, printing this on the box. That's a nice example of eliminating waste. It undercuts sales in the short term, but it's the right thing to do (plus boxes are just a few bucks each, can't be a high margin item anyway).
For those of you not using color coordinated tape, they actually give you three different places to mark the box's destination, for the first use and two re-uses.
Flow into a Dental Practice?
Dr. Bahri has used Lean thinking to dramatically improve patient flow to be able to do most everything in a single visit, instead of making the patient come back multiple times.
When I was walking on Boylston St., I saw a juxtaposition of businesses that made me chuckle:
To the left of the Dental Center is a store called, no joke, “Sugar Heaven” that sells candy.
My suspicion is that the Dental Center opened the candy store to help create demand! :-) I say this tongue-in-cheek that it would be single piece flow from cavity creation to cavity fixing! I don't think Dr. Bahri has ever considered doing this in Jacksonville.
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