Re: 20 rep squats
We ran the 20 squat program into our programming for about 7 weeks at my first box and saw some huge gains from our members. We started everyone at 60-65%, took a week or two for some of the guys with egos to realize that 65% was the correct starting point after they failed at 13-15 with higher % starting points.
Almost everyone was hitting around 85% for 20 by the time we concluded the program and most people PR'd there 1RM substantially. It's an effective program that I think fits well along side standard metcon programming. We only did it once each week.