If any question ever looks like it will take 3+ minutes, don't spend that time, even if you're 100% sure you'll get it right. You don't have to bail immediately - take some time to figure out an educated guess - but don't spend more than 2m before you guess and move on.
Every quant question has a 2-minute (or faster) solution, so if it's going to take you 3+m, then you're already at a disadvantage and more likely to make a mistake that will lead to an incorrect answer. Plus, you now have to make up that time somewhere!
On quant, as a general rule, you're going to average between 1.5 and 2.5m on most questions. It's fine to spend 2m15s or 2m30s on some questions because you're going to save 15 or 30 seconds on other questions.
Don't go into any question thinking that you're going to save time somehow. Start each question. If, around 1m in, you realize "I can't do it," or "I can't do it in a reasonable amount of time," or "But I studied this! I should know how to do it!" (that last is just being stubborn!), switch instead to educated guessing. You can take the time to eliminate wrong answers because you haven't used your 2m yet, right? Then guess and move on.
Read this article if you haven't already:
http://www.manhattangmat.com/blog/index ... anagement/