In my experience, American crosswords don't give you the divisions, so 10 spaces could be a 10-letter word or (3, 7) (5, 5) (2, 8) etc etc. I once spent a week trying to finish the New York Times crossword :)
at the risk of asking off topic, why don't the setters give the break of letters required - surely it would put off some puzzlers, especially 'newbies'?