Sometimes, our churches end up with some really big households in their accounts. I don't mean Duggar family big, I mean Father Abraham big. But these households are almost never intentionally created that way — they usually come from either a misconfigured CSV import or because we haven't always had Trusted People in Check-Ins.
These large households are unwieldy to work with and tend to break things, so there's now a limit to the size of a household of 20 members.
For some tips on how to best use Households in Planning Center, see this help article.