My son has extra time written into his IEP for use in tests but he has never used that. We have spent countless hours drilling him when he was younger with his math facts so that he could be "fast enough" (not the fastest, for sure) to be able to take tests with other kids and finish on time. Our other child doesn't have an IEP and has blown through the math facts in nothing flat.
I think it's foolish not to prepare for the ACT, SAT, etc. when they are taking it in high school for real. Like it or not, that is a major way colleges will admit (or reject) you.