Speeding up Formal Logic maps?

I'm running into a situation where I get most of the questions that require formal logic right, but only after taking a good 5 minutes mapping out the logic in the stimulus. If I don't go through this exercise I need to guess the answer most of the time (unless the logic is as straightforward as a couple simple if/then statements). I will obviously not have the luxury of all of this time on the test. Any tips on how to get faster at mapping out formal logic?