How do I manage time on the GRE quant section?

Before you write anything down or start solving, spend up to 30 seconds reading the question and thinking about the clearest, most efficient path to an answer. If you have a plan you're confident in, go back, carefully gather the details, set yourself up, and then begin solving. Moving slightly slower on an efficient route always beats racing off in a roundabout or wrong direction.

If you don't have a good plan within that short window, or you recognize that a problem is likely among the 4 or so hardest in the section, log a guess and move on. For "borderline" questions, use the mark function so you know to come back if there's time, after you've carefully answered all of the easier questions.

Others just aren't worth coming back to. Unless you're typically missing zero questions in a section (in which case we're not sure why you're searching for timing strategies), your goal should be to minimize the time you spend on questions you miss. Taking an honest look at a few problems and saying "I know I don't have time for stuff like this" is a smart, strategic move that gives you time for the rest.