Absolutely... you should always review your mistakes, no matter if it is
OG or anything else... you learn from them... I typically don't move on to another set of questions until I understand what mistakes I made in the previous set. And if I don't get it, still I try to memorize the solution if given or at least know the lead way to solve the problem.
In addition, I spend a good hour or more in reviewing my mistakes on the simulated CATs even though sometimes there are no explanations...
Also, you must of heard it on this forum that you should keep an
error log and categorize your mistakes to see which subjects you are weak at and therefore press those... The timing is also hard... I also get 30-35 in my CATs and don't finish all the questions, but usually at least first 15 are correct and then from 30 on I feel pressed by time! So pacing is the key I guess, and takes practice!
Good luck