I'm pondering washing the yeast from a batch that I'm bottling tonight. I intend to make a starter with it for my next batch. But my question is: with yeast harvested from a given fermentation, and then run through a starter, how do you know with any kind of accuracy how many cells you are working with, and therefore if you're overpitching/underpitching to the next batch ? Or is it more of a try it, and if it works, repeat... type of process ?