I voted for none because I am SO at my husband's maximum right now with four! Notice I said my husband's maximum! But, that was his insight with the second, the third and even the fourth...
And, each addition turn out to be his "little turd" as he calls them. If it were up to me alone, I'd gladly add one or two more! MY absolute maximum would be six! Any more than that and I'd have to take on a second job just for them alone - Vet visits, bathing, grooming, clothes, etc.
Yup, the whole second pay check would be just for them!