It's not quite like that - even if you don't try the more readily accessible combinations before the longer ones, but simply split your computational effort on each one in proportion (you'll find all of the 4 word ones have been tried when only 1/250000 of the 5 word ones have).
Not to mention that "chili dog monkey" are not exactly rare words and even a 10k word english dictionary would contain those.
Not to mention that "chili dog monkey" are not exactly rare words and even a 10k word english dictionary would contain those.