When do seasoning rules usually apply?

[Taft Love]

I hear about financing out of mortgages and loans often. However, what I don't know is when seasoning requirements generally apply. While I realize that non-conforming loans can choose their own restrictions here, let's talk about what's most common.

Under what circumstances do the seasoning rules apply? It seems clear that we have to carry conventional and FHA loans for six months prior to refinancing. What about cash deals, private lenders, or hard money?

I guess the fundamental question here is: do the seasoning requirements apply based on the deed, regardless of how the deal was funded, or is it based on the instrument?