actually, time management has nothing to do with minutes and seconds at all. if you are even thinking about minutes and seconds, then your time management is not good enough.
GOOD TIME MANAGEMENT is being able to answer 'yes' to the following questions:
• when you stop making progress, are you immediately aware that you've stopped making progress?
• when that happens, do you immediately STOP pursuing the path you're currently on (= the path that has led you to a dead end thus far)?
• ...and then, do you immediately start thinking about HOW ELSE you might solve the problem?
• ...and, if you don't think of any other method to try, do you immediately make a guess, and then immediately move on with your life?
if you can say 'yes' to all of these, then, congratulations, you have good time management.
looking at the clock should not even be necessary, except perhaps for psychological reasons. if you NEED the clock to know when it's time to move on, then the answer to at least one—and more likely several—of the questions above is 'no'.