Probably 4, two regular ones and the others much less so but no less good terms although everyone has to understand how to share properly.
I would want them to have others too and not just put their all on me.
In days past i'd have several and was content with this scenario.
Now i'm very happy with the one person I see but would still be open to the occasional one off encounter
For me, one fwb arrangement is plenty as it would entail a friendship and therefore something a bit more meaningful - without being a full on relationship. That wouldn't necessarily preclude one off hook ups as and when as long as everyone is up front about it. But that's just me, not sure there's one size fits all.