I watched a video once of a couple photographing a wedding. If the photographer wasn't "in the photo" while posing/prepping, the assistant was. When it was time to take the shot the assistant jumped out of the way, the photographer rattled off a few shots and one or the other of them jumped backed in to prep for the next pose. It was almost impossible for anyone else to get 'the shot' without one of them in it. It was beautiful to watch! lol
If I'm photographing anything where there are other shooters, before I take my shot, I turn around and ask them, politely, to please put their cameras down and wait until I have my shots for the client and then I'll let them shoot. Of course, after I'm done shooting I'm moving on to the next shot anyway.