l've noticed that my 5-incher who I am a very proud owner of, doesn't do the job when in cowgirl or reverse cowgirl. Admittedly, I'm a skinny dude who'se preference are curvy girls (I'm a German living in Spain so perhaps you can imagine my preferences). Therefore im not sure if the combined body compositions have something to do with that (some might say I can't handle" it basically), or if I'm doing it wrong.
A bit more detail perhaps: doggy and missionary are easy for me and prone-bone is by far my favourite position. But for example I had a Chilean ex who was hellbent on being on top for once and I said alright let's try it. She went on top but for some reason my dick kept plopping out. It felt like it wasn't long enough to be effective when I'm on the bottom.
Considering 5 inches is the average I figure I must be doing something wrong I keep hearing dudes say they love a woman riding them. Oddly enough I remember having sex (the best of my life) with another ex many years ago, and she was on top of me a lot, but in this case I remember exactly how I always bent my knees and held her cheeks with my hands while I was thrusting and she was whispering some crazy shit into my ears. Good times.
Anyway, I'm happy to answer any questions ofc maybe I didn't explain it well enough.