I think your best bet is to devote most of your time to weaknesses, with a little bit of practice for verbal as well.
I understand that the MGMAT series does a good job for quant. Did you use them properly, i.e. with solid review of concepts? Sometimes, when we're hit with a ton of info, we tend to not spend enough time on processing it.
Were you dissatisfied with MGMAT's approach? Then maybe you should consider buying another strategy book - like the Kaplan Math Workout.
In the end, you should have a book/a series at your hand for concepts and also buy the OG quant for more official practice. If you feel you can't remember the answers to the quant portion in the OG 12, you could just review that one. That is, as along as you feel that you are using your skills to solve a question and not your memory.
I also suggest browsing this forum for problems related to your weaknesses in quant. You can use the search function, using keywords such as "permutation" or "circle" to get some targeted practice with answers/explanations provided by forum members.