As long as everybody consents, I don't see a problem with it. Speaking as a woman who has had moderate amounts of casual hookups/FWB situations in her time.

I will say though: one night stands, in my experience, can be pretty hit or miss; I find for me to really enjoy myself I need time and at least two or three encounters with the same partner before we get into a groove, so to speak. Once we figure each other out, the sex becomes MUCH better.

So IMO a FWB situation is much preferred to one off hookups; I don't need to be in love with someone to enjoy sex, but knowing what makes them tick and knowing they give at least somewhat of a shit about me really helps to enjoy myself better.

That's not to say one night stands can't be fun for me. They can be. But it's more psychological than physical, ironically enough. If I actually want to get off, chances are, I need more than one encounter, so I can get comfortable with them.

Anyway, that's just my opinion and experience; I cannot and will not speak for all women. But if you want your casual sex experiences to be ethical and enjoyable for you and your partners, consider what I've said above. Again, I only speak for myself, but I'm positive I'm not alone.