I have not noticed any problems with my negatives and I don't tap.
There are two reasons I "tap."
First, depending on how I'm transporting and carrying holders, the film can work it's way up a bit, which then allows the code notches to impinge a bit on the image area. Most of the time, this isn't an issue, but I still like to have them squarely in the film rebate, not in the image area.
Second, and more importantly, during long exposures, especially if there is some temperature variation between holder and ambient temperature, the film that has not been seated properly can slide down during the exposure, ruining the exposure (don't ask me how I know...).
So, for me it's tap once with the flap side down to seat the film in that orientation. Then, if I'm shooting in "landscape" orientation, I'll tap again along the long side to make sure the film is all the way to the "bottom" for the shot. It just takes a fraction of a second: " tap-tap-insert-pinch-pull slide" and is good insurance.
Best,
Doremus