Check this page. I refer particularly to this sentence:

Quote:

Worse yet, the thirty-second nature of a small fish's memory guarantees that they can never, ever get used to it.



I submit that the use of the hyphen increases ambiguity rather than decreasing it. A hyphen would normally be used to indicate that this was an ordinal number rather than a measure of time, but the context seems to suggest that it is the measure of time that is meant.