... if you really take a hideous detour from the "right" track, your characters will get more and more uncomfortable. Because if your characters are any good whatsoever, they have unfinished business, and your detour is taking them away from it for no good reason.
Charlie Jane Anders at io9 on writing out of a dead end. Read the whole thing, it's good. This was the quote I chose to highlight. There could have been dozens others.