Two students take the same 50 mocks. One clears, one doesn't. The difference is almost always the review.
After every mock, categorise each wrong answer: (1) didn't know, (2) knew but misread, (3) knew but ran out of time, (4) silly mistake. Each category has a different fix.
Spend at least 90 minutes reviewing a 60-minute mock. If that feels like too much, you are taking too many mocks and learning from too few.