GM2409
I haven’t taken any mock tests yet. I have practiced questions from the Official Guide. My quant is quite strong, but I am weak in the verbal section.
Mock test will help you gauge your current level.
Plus, I appreciate your strength with Quant. Though the questions aren’t that difficult on GMAT. Yet solving them within time and maintaining the accuracy of untimed will be tested with mock tests.
It’ll help you with the real picture.
Just sharing my personal experience; I used to think I’m strong at Quant, but depends how long you’ve been away from the maths. For me it was a quiet some time, and I realized I was doing silly mistakes while solving problems in TIMED manner
All the best for your preparations