spgny
peaceyall
if you need extra practice beyond the OG, then they're useful. otherwise, OG should keep you plenty occupied.
only issue I found is that it felt like the first 1/3 to 1/2 of the questions in OG were not that challenging...I would like a resource that provides more challenging questions.
I felt challenging questions were the key the first time through. I did a lot of the questions here and CAT after CAT. That regimen produced a Q39.
The second attempt, I just relaxed and did all of OG and Jeff Sackmann's GMAT Math Bible... much less challenging, but I went up to a Q48. Either I botched the first time badly, or repetition at level worked better for me than stretching above level.