I agree wholeheartedly.
I find these posts of the same aircraft as posted before, but in a lower quality, very annoying.
If there's already a post on an event I have attended, I like to check first if I can add anything new to that topic. That can be a picture of a particular aircraft that's not already in the thread, a picture of an aircraft under a different angle, or a better picture all together.
An exception, annoyment-wise, can be made for explicit requests for advice to make it better the next time, but you don't need to post 20 pictures to prove that you really can't produce anything sharp or exposed correctly.
Does that mean that only the really good photographers can post? Certainly not! There's always a few aircraft left that "they" haven't posted yet. If you really don't have anything new to add, but still you need your name displayed on a forum, at least limit yourself to the one or two least unsharp ones
And of course you can always go to an event where nobody else goes, so all the scoops are yours to post, like
here (a completely conspicious attempt to advertise my pics of Tannkosh, where nobody else was
)
Marcel