Well, I can't respond from the science angle. But I can respond from the practical application angle. 20 rep squats are the cornerstone of my bulk routine.
If you see me doing 20 rep squats, that typically means that it is day one of my bulk cycle. Nothing, and I mean nothing, has been as effective for me for putting on substantial muscle than 20 rep squats.
It's just like you stated. Pick a 10 rep max squat weight. And then rep it out for 20. How? When your legs are starting to shake at about 9 or 10 reps, take deep breaths in between each rep; you may need up to 5 or 6 seconds between each rep to recover enough to do another one; and then bang out another. Repeat this until you hit 20 reps. Then drop to the floor and try to collect yourself and not throw up.
I'm a masochist however. A lot of times, after that initial set I will bang out 2 more sets of 10 reps at a higher weight. And then I will do some one legged squats and leg extensions to polish it off. Oops, I almost forgot to add that I'll do a couple of sets of seated calf raises with multiple drop sets built into each one.
A lot of volume you say? Yes. But I will only do this on the initial day and then eat like a pig and sleep like a sloth. I won't repeat 20 rep squats the rest of my bulk cycle which typically only lasts 2 1/2 to 3 weeks tops due to CNS burnout. But let me tell you, when I go in for my next squat session during my bulk cycle I've immediately added major pounds to my squat number which equals more muscle.
I've done this over the last year or so averaging about 3 to 4 bulk cycles per year and I'm the largest I've ever been. 20 rep squats are not for the faint of heart, but they work oh so well.