This is my thinking on it, i have eight at present, I could probably make do with four if I had the perfect ferret at the right age every year, four good ferrets could just about outwork me if I was out three days a week.
Now the reason behind having a few, different ground, needs a different approach, some of the slopes and lowland are deep warrens, hence a couple of decent jills to move the rabbits, then on the high ground with shallow digs, a couple of decent hobs to get the job done fast with no nets.
Then the part that shows up how soft some of us are, my oldest at 6 now is still