I would say to those who are new to this, whether bull, cuck, hotwife, girlfriend or whatever, maybe try it out with one or two guys with the girl first.
Whilst the focus should be on the girlfriend/ hotwife, one thing I would also point out is that the sexuality of all the males involved should be aligned.
For example, if the cuckold is bisexual and the bulls having sex with his girlfriend/ wife are also bi, that would make sense. However, if the bulls are hetero and the cuckold tries something, I can see trouble there.
Similarly, it might not appeal to the cuckold/ girl if the bulls are bisexual and the focus is not primarily on her.
Several hetero bulls and a hetero cuckold would probably be enjoyable for everyone concerned though.
Nonetheless, if the girl enjoys multiple BBCs and the boyfriend is happy with the arrangement, go for it.
I think a white boyfriend watching multiple black giants pounding his girl's pussy while her leg tremors and she squeals at the mix of pain and extreme pleasure, is the ultimate in sexual pleasure for everyone involved.