I've used L/R balance as an aid during recovery from a bad injury.
I also use it to detect when I'm beginning to fatigue, my balance shifts when I'm overtraining.
I'm typically 51/49, 50/50 or 49/51. When I get fatigued it can go to 55/45 without me feeling it.
I also find that in low power output, (especially on Zwift) balance can range from 35/65 to 65/35, but once the effort goes up my balance gets close to 50/50.
I have a set of Favero Assioma Duo's and also a left-only PM
After realizing that balance can easily be 48/52 or 52/48, single sided PM's have a fairly wide range of inaccuracy due to the doubling effect.
In most instances this doesn't really matter, but in training at specific numbers it could.