I mean they don't reshoot a whole movie. They are also working on cgi and effects for shots from the time the first shot happens so a lot of that work is already finished well before the movie is being done shot.

And I don't believe they are done with shoots, usually audience testing leads to one or more things being redone.

Personally I wouldn't give any of these rumors too much credit, all we are hearing at this point is that someone heard someone else say something. That's usually not the kind of evidence you wan't to put your bet on. Don't forget, there were people that didn't like the Punisher because it was too violent, and they didn't like Deadpool 1 because of its crass humor. Wait until some user reviews come out.