I've done 1 leg split squats on the smith and with a bb, and I feel like I got a better workout from the smith machine only because my balance is fucked when doing bb.
Ultimately I need to do more bb work because of what's said about squatting with the smith.
But to answer your question, I go until my knee is just about to hit the floor and at this point the top of my leg is parallel with the floor.
oh you're talking about split squats. those technically aren't single-leg exercises cause you use the rear leg to stabilize. I agree though, they're totally baller. I don't feel them much in my glutes personally, more in my quads, but that's because my quads are my weak link.
My current routine basically has this for the max effort leg day:
squat or deadlift variation - work up to 3-5RM
split squat or lunge variation - 3-4 sets of 8-12
posterior chain exercise (i like RDLs) - 3-4 sets of 8-12
high rep ab circuit (3-4 exercises no rest between, 2-3 sets)
then the "dynamic" leg day looks like this:
jumping exercise (plyometrics)
3 sets split squat or lunge with front foot elevated (more ROM) - 3 sets 8-12
posterior chain exercise - 3 sets 8-12
weighted ab exercise - 3 sets 10-15
I think any growth I get from my legs will be from the split-leg training since the squats and deads are so heavy. I think if you can't do split squats with a BB you should try DB's... that's how I do it just because it's nice to feel a burn in my traps. I have trouble stabilizing on my right leg in particular, but I've gotten used to it now. Always start with your weaker and less coordinated leg.
sorry jonno your log officially got skeletor'd/jmezz'd