Maybe I should do some light back squats on the other leg day just to keep form practice to more than 1/week?
depends. if improving squat is high-ish on the list of goals, or if you feel like form is inadequate on the ramp-up and heavy sets, then yes. if you're just concerned about size or general strength and if you feel ramp-up form is adequate if less than perfect, then don't sweat it.
also do them twice a week if you, you know, enjoy them.
EDIT don't listen to me on that point because i love squatting and have been known to let it get in the way of other goals. eyes on the prize.