Everyone above is of course correct that you are not scored directly on timing. However, I'd like to caution you that a 3+ minute problem is typically one you're getting wrong, and even if you get it right, there are potential problems. First, you may run out of time later (this is one of the most common problems in all of test-taking) and second, you may still get zero credit! Many of the problems on the official test are experimental and do nothing for your score, so it's not wise to knock yourself out on any one problem at the expense of others. You are best served by keeping your time fairly consistent. Certainly, some problems will take longer than others, but I can tell you from years of looking at people's test timing that it's a very rare student who can spend 3 minutes on many of the problems without running into trouble at the end and reducing their score.