What do you count as a batch?

I count each F1 as a batch. I usually have 2-3 F1s going at the same time, I count each of them as a batch, so that's 2-3 batches at once.

I count my F1 containers as 1 batch each. But I have heard of people counting their F2's as batches, since from 1 container of F1 they could make 4 different F2 flavors, each their own "batch".