I can see why one would think they know everything about a field just because one "has a good general knowledge of the field, up to date with recent research, and have publications of your own" for the following fact (noted by Donald Rumsfeld)
"There are known knowns; there are things we know that we know.
There are known unknowns; that is to say, there are things that we now know we don't know.
But there are also unknown unknowns – there are things we do not know we don't know."