I think with 4 weeks to go, one practice test per week is the best approach, and for you it sounds like that means (as it does for most of us) on Saturdays. By now you should (hopefully) be pretty strong on your concepts, so the challenge isn't so much learning specific details on each question type but learning how to put those skills into practice on test day. A great GMAT teacher I once knew called this "closing the cap between what you can do and what you actually do," and the best way to improve this skill is by actually practicing CATs, where the question types change back and forth all the time and you have to learn to roll with the punches.

Good luck!

Thanks for the strategy, Adam. It makes sense, in terms of getting used to connecting the dots quickly and efficiently.