So, maybe it would be safe say; when your doing a heavy leg day, and I mean heavy weights, that you should maybe do partial and/or half ROM.

NOTE: Not to be confused with half ass!!!

And when you do lighter leg days, meaning lighter weights, then it would be okay to do full ROM.

I do both and I still got good knees at 42 years old.

ALSO, very important: Always stretch, and warmup before squatting... Just like everything else, but definately when doing this exercise...

That's just IMO...