It really depends on whether or not you love sailing. If you love it, don't look at the map and explore everything. If you get bored after spending real life days of not finding what you're looking for, to the point of not wanting to log in, then go look it up.

I don't think of it as cheating. Most of the time I do look it up. But I've decided to try not doing it on this playthrough. The trader wasn't that bad, but finding a good swamp that wasn't merged with the plains was driving me nuts.