It also assumes that you buck cut the log from the same side all the time, If not, the device has to be removed and then re-attached to the other side of the bar or you have to go to walk around to the other side of the log being cut.
I like using my bar length as the ruler. It's easy for me to use and always available when measuring to the right or to the left.
It takes about 2 seconds to move it to the other side of bar.
Your method works too, and that’s cool.