How long is too long?

I keep my hair long, or rather, just past shoulder length because A) I like my hair long, and B) so does my husband.  Plus, I can put it up in all sorts of ways, pull it back, tie it, braid it, roll it in a bun -- the possibilities are endless.

But how long is too long?  I saw a lady at the grocery store whose hair was all the way down past her butt!  It was braided, and looked like it needed a good trimming to get rid of all the broken ends.  No telling how long she had been growing it.  Plus, it has to be a pain to wash, not to mention getting it caught underneath you or behind you when you sit or sleep.

Is the fact that women don't grow their hair to such lengths because they can't?  Or because they know the extra time and trouble it creates?