This is a good question, and I have to say the hours and hours comments seem exaggerated to me, too. But what do I know. I remember a bud I used to jack around with in college who took forever to cum if he was beatin or whatever. I could sometimes hear him in his bed beatin off and it was FOREVER. For me, I sort of got used to cumming quickly in j/o sessions.
In sex, I usually last an average of 15 min for the first time. This is after penetration and with a woman. If I'm using a condom, then longer, but I don't like that. My wife is not a multi orgasmic usually. I've definitely taken her to 3-4 orgasms before, but usually that's post my orgasm and with manual stimulation. If she cums before I enter, then I'm not gettin in, so we don't do that. She says she's just TOO SENSITIVE then. I can relate.
In my experience with m2m sex, I can last longer...much longer. But in that case it's usually lots of different positions, and it's covered for sure, so there is less sensitivity. This isn't part of the question, but I find vaginal sex much more stimulating for me than anal as a top. So, while they're both good, I last longer on anal than vaginal.
Of course, MOST of my vaginal experience is with my wife, and my goal isn't long lasting as much as pleasing her, then me.