What do you mean by distinct?
If you look in the past 1880-1940's pretty much had the same fashion trends, so their was no distinction at all. It would seem that with technology we are granted the opportunity to make distinctions. If anything I'd say they are becoming more distinct.
But obviously as others have stated seperating it into decades is inaccurate, and future historians will probably re-name them, but for now it would probably be as accurate as anything else we could come up with.