I'm jealous of brewers who are able to make good beers with older washed yeast. My last two batches sucked and I'm blaming the washed yeasts. One used 6 week old 002 that was probably full of trub from the previous batch. 002 is hard to wash! The other was 2.5 month old 001. I made starters on both and both fermented pretty vigorously. Both, however, have the same green apple background flavor to them. Needless to say, I dumped them.
Perhaps I didn't wash as good as I could have. Either way, I'm a little gun shy with washing yeast now and have opted to split off part of my starters to keep for future use, keep the yeast as clean as possible. I feel like the shelf life should go up with less trub in the yeast. That's my hope, anyway.