I took the SAT like...five years ago? There wasn't time to doodle or screw around. It was three hours (with two five minute bathroom breaks) of solid testing, essay writing, etc. I skipped the practice test, because it was a load of BS...almost as much a load of BS as the ASVAB.
I got an SAT study book and spent like, a couple hours a week for about a month going over SAT words and practicing the essay and math portions. I made an 1840, so...make what you will of that.
I would have taken the ACT too, but I didn't have the money at the time to take both along with all the AP tests I was taking. I heard the ACT was easier than the SAT, so I kind of wish I'd taken it.