Why Start the New Year with Blank Charts?

Charts like this always make me wonder why we throw away the additional context of data from 2016 when we start the 2017 chart.

It’s unlikely that January 1st in any given year is the magical creation of a new system or a new process. In other words, January 2017 was likely the same process as December 2016. The annual cutoffs are arbitrary. Sure, people are accustomed to thinking in annual cycles, but is this helpful for improvement?