Hmmm. Tricky one, and I am taking the question seriously.
I think if you go out with others there is a very definite point at which you can be seen to take the piss.
If you want extra riding, I reckon you should go out by yourself, or go out early then meet up, or ride after they have gone.
If you are the fittest, it can be soul destroying having to wait around, but it's far, far worse to have the fit guy ride to the top then come back down and ride up with you while you are breathing out of your arse.
Basically, if you want training, ride alone or with a fit mate, and if you ride with others of lesser ability, you have to suck it up and ride at their pace.
If I'm in that situation, I would make sure I was last, I would make sure that the last guy was ok, and that I stayed back far enough to let him ride at his own pace.
On the road, I would stay back too, but try to ride up the climbs in a silly big gear so that I got training, but never left anyone behind.