High reps can be very productive for squats. The 20-rep rest pause set of squats will probably be the hardest thing you'll ever do. Load the bar with a weight you would fail at 10 reps at, and then take lots of heavy breaths once you get past the 10 mark, until you eek out 20.
It's brutal, this set can take at least 5 minutes.
I either do one set of these, or two sets of 5.