I made three straight batches of Wheat beer on one vial of yeast and they all turned out great. 'Standard' hefe, dunkel weiss, then a blueberry. Most of my reading suggested that pitching on a trub more than twice was asking for trouble, so after the third batch, I tried a 'wash' and then saved some for future attempts.
The "west coast ale" yeast currently in primary will see a Pumpkin ale in a few days. It's a great way to stretch your yeast dollar, and if it goes bad, it's not the end of the world.