Well i'm not sure what your goal is, but your 740 on the last
MGMAT CAT is quite encouraging. It might be worth while not taking anymore actual practice tests. A 740 doesn't just happen by mistake (unless you saw repeat questions). At this point, reinforcing topics you know, and going over your
error log, or missed questions in CAT's along with questions you got right, can help you reinforce all those topics. If your goal is a 700+, and you are in that range from your practice tests, then you don't want to burn yourself out on the last 2 days, or have a poor showing on a CAT and crush your confidence. You should have VERY high confidence after a 740 CAT. Plus,
MGMAT quant is considered slightly harder than the real GMAT, so it makes sense that you would be feeling that way. Keep your head up, don't burn yourself out, work some practice problems, review concepts, and keep yourself fresh for your test. On the last day before your test, definitely don't take a practice test, and don't burn yourself out.
Good luck! We look forward to your debrief