Your one of the people that inspired me to try this to begin with. Reading your log where you did something similar for a week. Also watching Kai Greene "a day in the life" (you tube it bro...inspirational)
I'm doing 5x20 on everything now not just legs. Its brutal. But its working. starting week 4 today. I cant go ass to calves because I have a torn ACL. But to the OP if you can go that low, do it. But at the very very minimum, go parallel. Make sure your squat for is spot on. I see too many guys doing fucked up squats out there. Youtube is full of videos for squat technique.
Another piece of philosophy....(copy and paste)
Ever notice that you FEEL the muscle better on your warm up sets than you do on your "working sets"? Isn't it so true that the lighter weights often burn way more than the heavy ones? Why do you think that is?
Well, one of the main reasons is that you're not focusing all your attention on stabilizing a weight and barely moving it from point A to point B, likely using every muscle in the general vicinity to get it to move and the range is WAY smaller than it was with the lighter weight.
The PROBLEM here is that the TENSION has SHIFTED everywhere BUT the working muscle!
Your body adapts and starts using anything it can to keep itself safe. You can continue lifting heavy weights, all day long, but without optimal muscle tension, don't expect to see any improvement in your skinny arms and legs! If you can't "feel" your muscles then you won't be able to exhaust them enough to illicit the hormonal, metabolic and nervous system response for muscle growth.