It varies a lot!
sometimes, we haven't seen each other in a long time (meaning a week or so) and then it might be quicker then we both expected
But when we're both well balanced, i guess it can be from 15 minutes to 30, maybe 40 minutes... it's hard to put a time on it... i remember once that i did look at the clock (before and after) and i was surprised how long it took
But for us, to both make us last longer, i think we'll need some condition-training! Usually i can't "ride" him longer then five to ten minutes or so; after that i'm totally exhausted, and he has to do the finishing job
;
Any of you have any tips on this, for me to last longer physically (by wich i mean, that my mussles -in my legs and so- don't get so tired so soon...) ???