I am aiming for around a 720 on my GMAT. I am about 4.5 years out of college - took a diagnostic with no prior studying and got 580:

35 Q (10/31 incorrect...10 unanswered b/c ran out of time - about half of the questions wrong were from number properties)

35 V (10/41 incorrect...5 SC, 4 RC, 1 CR)

I've spent about two weeks studying so far (plan on taking test in early June although I'm flexible as I'm applying to schools in October), and have really only spent that time on number properties. I've probably averaged 15 hours study time per week (although I have not been closely tracking). I think I got the basics down but I think I made a mistake in moving onto the advanced sections, where I am seeing how rusty my skills are. Should I just move on to studying the other areas as I feel as though I am spending too much time on this - and then if I find the other areas I am breezing through then come back to number properties later on and really focus my studies towards this section at the end?

Can I still get a 700+ without focusing on the advanced portions of the number properties guide (I hear that this is the guide to focus on to build a "foundation" for your math skills)?

Any input would be greatly appreciated!