Rack pulls:yes. Half squats:nope.

[tsoukase]

I would like to ask why partial-ROM movements are "good" for Deadlift and "bad" for Squat.

One reason is that the partial-ROM DLs (eg. Rack pulls) do not stress the joints asymmetrically, while any squat higher than parallel strees at least the knees inappropriately. If it didn't, overloading half-squats near the sticky point would be a very good assistance ex. to increase the weight of the full movement. Your thoughts about this?

[Adam Skillin]

I would like to ask why partial-ROM movements are "good" for Deadlift and "bad" for Squat.

One reason is that the partial-ROM DLs (eg. Rack pulls) do not stress the joints asymmetrically, while any squat higher than parallel strees at least the knees inappropriately. If it didn't, overloading half-squats near the sticky point would be a very good assistance ex. to increase the weight of the full movement. Your thoughts about this?

I think the knee position is definitely a part of this phenomenon, as well as the fact that a partial ROM deadlift is quantifiable in a way that a partial-ROM squat isn't. That is you pull from the pins (rack pull), or until the bar is above your knee (haltings), but a partial squat can just be more partial unless you are talking about using the rack pins or a box.

[Sean Stangl]

It might help to think of rack pulls as an "overload" type movement instead of a "partial" movement. The goal of overloads is to handle significantly more weight through as much ROM as feasible to address a specific weakness at the top of the movement.

Instead of comparing rack pulls to partial squats, I think they're closer in effect to squats with chains and Slingshot bench.

Edit: Actually, now that I think about it, I think it would be reasonable to do half squats in a quantifiable way using pins. There are probably better options, and the setup would be weird, but if you're trying to strengthen the top part of the squat, it makes sense to train the top part of the squat directly.

[BarryF]

Has anyone ever failed a squat once they were more than halfway up with it?

[Sean Stangl]

The sticking point is typically somewhere around halfway up, when the hip drive typically cuts out and the hips transition forward.

[hamburgerfan]

Has anyone ever failed a squat once they were more than halfway up with it?

Yes.

[Adam Skillin]

Has anyone ever failed a squat once they were more than halfway up with it?

I have, once. About 0.5" from lockout. But it was rep 10 of a 9RM (in hindsight) bone-on-bone grinder set, and I just got the "being electrocuted" shakes and melted like warm wax down to the pins. It wasn't that the top part of the squat was weak, it was that I was already squatting on fumes and absolutely ran out of gas.

[Nate7out]

I agree with Sean. It might be a good idea to do a partial squat down to the pins, or going up starting from the pins as some sort of assistance movement. This could be overload in addition to squatting.
Andy Baker has an article about pin squats on his site, can't remember if he addressed partial ROM in that one.

[51M0n]

Paul Anderson did a lot of partial squat work if memory serves me correct (I believe he used concrete filled barrels and dug a pit to the depth he wanted).

[Les Hahn]

Paul Anderson did a lot of partial squat work if memory serves me correct (I believe he used concrete filled barrels and dug a pit to the depth he wanted).

Yep! :-) It makes sense to do partial squats (to a set depth) as an assistance exercise to work a weak spot. Most people don't fail right out of the hole, even raw.