Repeating the same mistake a thousand times just makes it a very well-trained mistake.

Repetition does not improve anything by itself, it only makes whatever you did more automatic, including the error. Hours of practice with a flaw baked in produce a very reliable flaw, and it gets harder to remove each time because it sits deeper. Volume only helps once the thing being repeated is correct.

Before the next long session, get one person or one recording to check what you are actually doing. Fix the pattern first, then pile the repetitions on top. Slow and correct beats fast and wrong.