I love to keep going after I cum! Yes, my head gets a bit sensitive, but not so much that it bothers me. I also go from fully hard to about 'half-hard' so I'm sure my head shrinks a bit. (One girlfriend said she enjoyed me more after my orgasm because I fit her better). After a couple of minutes I get hard again and can keep going until she's had enough, but it usually takes quite a long time (like 20-30 minutes) before I can cum again, and on the second round I can usually hold it as long as I need to. I rarely have ever gotten to a third orgasm, though, because by then it's well over an hour of continuous thrusting and one or both of us is tired and/or getting sore. In fact, I don't think I've been able to do that for close to 20 years.