I went from 275 to 315 in about four weeks by doing the pin thing. 315 felt like it was going to crush me before I started forcing myself to do this, now it is no problem. I also got 295+55lbs of chain off a 14" box last week with no rocking, so just handling heavy weight seems to do it for me, not repping medium weights. I am working on 365lbs now and should get it in a few weeks.
Dont do this without a rack or something. Right after I got 315 below parallel I thought I could do a quarter squat with 375, and it felt ok until I tried to stop and I kept going into the pins.
I also moved my DL from 405 to 425 in the last month from doing this, I stopped doing DL about six weeks ago after getting 405.
I think this mostly works just because the weights are relatively light, I am 198 bw, so just getting used to the heavy weights is what is important.