The reason I do partial squats is more practical than theoretical.
I need a strong stimulus in order to maintain strength just before and during the competition season.
Since I only lift twice a week, I can’t handle large volumes of squatting without getting sore and impacting track and OL training more than desired, and that impact grows in significance as the season progresses.
So, I use partial squats, pretty much with the same weight as full squats, in order to both get sufficient training stimulus and not mess up the rest of my training. I might vary the speed of execution, but that mostly depends on how I feel that particular day.
Oh, also, if I do full squats throughout the whole year, I won’t be able to find jeans that fit at all.