What do you guys do when you have a couple minutes left (~5 min)on the math section? I completed all the questions I skipped; the problem is there isn’t enough time to recheck the whole thing, but I still have valuable five minutes which I don’t want to waste at all so what is the most effective thing to do?
Sleep. Prepare for Reading. Or go to the restroom before the official break starts (when everybody rushes to the toilets and competes for limited slots). Or probably get a head start on Reading (if the proctors don’t watch you closely). Or, most reasonably (hahaha), check back on math questions that you think are really easy, because these are the ones where you are likely to make careless mistakes. :))
ACT question presentation is very straightforward, so careless mistakes are very rare. You don’t really need to check anything if you’ve solved it all, so start mentally preparing for the next section.
@Hermit9 It is strange for me that the more straightforward the questions are, the more careless mistakes I will probably make. Once I did a practice reading section, and the question asked “which of the following occurred last chronologically?” And I spent literally one minute to look for all four answer choices in the passage, and chose the one that occurred first chronologically… lol. I was so mad about myself, because I’m absolutely confident about their chronological order, but just chose the wrong end.
@AmericanGothic I’ve found that getting in a pre-test routine that makes myself calm yet focused helps me avoid that. I always listen to Kind of Blue by Miles Davis and read the Tao Te Ching right before testing so that I don’t lose focus. Try coming up with a routine of your own to combat those careless mistakes.
I literally just list all of my careless mistakes and read them right before I go to the test center. Believe it or not, it helps
I wish I had five minutes left lol
OP
recheck your answers with the time you have left.
Do no skip ahead to reading. You can get caught, I have seen it.
Use it to recheck some of the trickier questions.
I usually make a mark next to some of the problems I’m not sure of and just go back to them to double check if I have the time. Usually, my first answers are correct, but reassuring myself of the fact does help to relieve some of the anxiety I feel 
(The ‘OMG what if I got that question wrong because I didn’t recheck it!’ anxiety.)