That subject got you reading!
Have just slept with internet chappy, who informed me immediately prior to having sex that I should look forward to five hours of undiminished pleasure. I pointed out that five hours of it wouldn't, in my humble opinion, be particularly pleasant, but rather bloody painful, and in the end I gave him about two hours and then feigned sleep...
Anyway, it got me thinking. How long do you girls and boys think a good shag should take???