I've read reports of 75-100 pounds added to a 1RM.
You most definitely work for it though.
With squats four times a week I couldn't imagine doing much else. Maybe one upper body maintenance day. Bench, OHP, chins, dips, seated rows all done in the 8-10 rep range.
The added squat strength and leg size is very tempting though. If anything I'll run the smolov jr just to see if I have the testicular fortitude to see it through in the future.