Yeast bank
Kveik has been passed down through generations of Norwegian farmhouse brewers. This is my small version of that: every starter makes the yeast for the next batch, and each saved jar is logged here.
How I overbuild
Instead of pitching a whole pack, I make a starter that's bigger than the batch needs. Once it has finished, I pour off amount into a sanitised jar for the fridge and pitch the rest. That jar becomes the next generation, and the next starter is built from it.
The original pack counts as G0. The first jar saved from it is G1, the jar saved from a G1 starter is G2, and so on. I start a line again from a fresh pack after G?, or sooner if fermentation slows or the flavour changes.