It really depends on what I'm doing, if it's oral then please continue...but not for too long. If it's sex then I will continue until she tells me to stop as I don't lose hardness just because I've orgasmed although I am a lot more sensitive.
Most of my past partners would slow down or stop just before ejaculating. It depends on the guy and the mood. I've had guys that carry on thrusting as they cum too.
My husband slows down but keeps thrusting - just slower. Some guys depending on the situation or mood can still carry on thrusting even after they've cum. Condoms desensitize the penis a little and there are some condoms that have a desensitizing gel in the tip. My husband sometimes uses one of those if he feels like thrusting or being inside me for a long time. He can go from hard to soft to hard again with one of those.
If I'm giving my husband a hand job, he likes it when I carry on jerking him off as he cums - says it makes the orgasm more intense but when he's done I have to totally stop or slow it right down and only stroke close to the base of his penis. The tip of his penis is a no-go area for a few minutes after cumming.