I am baffled with my variance. Probably because I haven't trained.
Yep. Exactly. :)
In general, I'm not aware of any school that would look at a 710 and decide not to look at the rest of your application. It should be good enough to get you a "GMAT? Check!" response from the vast majority schools, and what will really matter is the rest of your application.
Now, depending upon the specific school, there is one possible area of concern. A few of the very top schools want to see what they call the "80/80," which means at least 80th percentile in each of the two sub-sections. It's okay if you're in the high 70s, but your quant score on the last test is only high 60s. How much will that matter? It depends on the rest of your application. If there isn't really anything stellar somewhere else in the app, and if you don't have other strong quant stats (classes in school? work experience?), then it could matter.
I don't know which schools specifically hold to this standard or how strict they are, so you should go post your question in the Admissions Consulting folder. Tell them which schools you're looking at, your scores, and any other info you think is relevant.