Another good reason for adding at least a few subtle side markers (I use the Gollihur stick-on type): if you have basses with different mensures, string heights, etc.
I learned that to my chagrin recently, when my pickup stopped working at a gig. No problem, I thought—I pulled out the Yamaha Silent Bass I brought as a backup and carried on.
But the string length is a good 1.25 inches shorter, the strings are a different thickness and the bridge is much lower with a more shallow radius. It was a challenge enough adjusting for the last two factors (especially when bowing), but the different mensures meant the notes were literally in different places. I didn’t do my best playing.
I’ve used the Silent Bass as my primary player for months at a time, and I didn’t have a problem. But you don’t switch over to a new set of muscle memory, just like that. A few side-placed position stickers are going on and staying on.