Any one know how many times you can do this? I have a recipe that I really like and I'm trying to nail down my numbers for all-grain. This is what I have done so far. Made first batch pitched new packet of nott. Made second batch and pitched it onto first batch yeast cake. Going to make batch number three this weekend. Should I use a new packet of nott, pour onto same yeast cake or wash said yeast cake and make a starter with it?
I'll personally only use the cake twice (for a total of 3 batches) - though I've heard you can do it more. Probably not true, but it just seems like the risk of infection and/or risk of off tastes from the trub that's accumulated would go up with each re-use.
And, when washing yeast, I'll only wash the yeast when the cake hasn't been re-used - I'm sure it doesn't matter, but it's what I've been doing and it works.