Too many aren't rating puzzles. Personally, I don't use my own time to determine the rating, because if I make a mistake (marking northwest column instead of northeast, for example) and have to restart, that doesn't mean the puzzle is difficult. Some clues are more difficult because you can't use them until you progress to a certain point. If the names within a category are too unfamiliar or similar to one another, that puzzle would also be rated harder.
I wish it were possible to rate a puzzle after giving up, without solving.