A conversation yesterday brought up the Dynamic Systems Theory. When you move, for example a squat, your next squat will be slightly different. There is no exact repeated pattern.
Reading a PRI conversation with Bill Hartman this was again addressed with the idea the variability in movement is good. A study showed that in people with low back pain the paravertebral muscles in only one spot moved doing a repetitive task, the pain free backs had variable areas of movement. Back Pain.
Heart Rate Variability measures the R wave to R wave. The more variability there is, the greater the health.
A study that I couldn't find, showed that runners that varied their cadence and strike pattern had less percentage of injury. More trail running perhaps.
It seems we are hard wired to have variation in our systems. This is a good thing. The more variation we have, the less dysfunction.
Perhaps the only thing we really need to do is to work on the joint mechanics so that our joints have full pain free ROM. This then gives the brain and body more options to produce the particular squat you are attempting to do or attempting to analyze.
Variation is a good thing.