I got seconds a time or two with my wife, but quite honestly by the time we did a mmf she was pretty well exhausted by the time our lover came in her. So I got to fuck her during our play time, but usually the other guy would cum in her and she was pretty well worn out by then. I didn't complain, because I got to fuck her and suck cock and eat cum. My kind of night.
I agree, going second or third bareback before any cleanup is truly sensational. I was in a long-term relationship with a married couple who needed help to meet her needs. He was ten years older than me while she was about fifteen years younger than me and very fit, truly an energizer bunny. Most of the time I went first because I was good for five+ shots on goal during our sessions, and I was fine with that - he was sharing so I accommodated their wishes. But once in a while she desired him first and I followed by entering her within seconds of him pulling out. Heaven!
I was lucky enough to be the 3rd guy to fuck a lady one time. I was at a swing/nudist resort and was in a small group party. 2 women and 5 men. I was third to fuck one of the women. It was an incredible feeling, sliding my cock in to a pussy that already had 2 loads of hot cum in it. It was so fucking hot feeling all of that cum surrounding my cock and leaking out on my balls while i fucked her. It didn't take me long to add my load to her pussy.