These theories are based on my experience with a 20ga and a 28ga smoothbore. It may not work for you but it sure did for me!!! Good Luck and keep experimenting, that's how we learn!! Buzzard
Personally, based on my own experience, I think you're absolutely right!
Holes in the pattern (Doughnuts on the pattern board) can definitely come from the fiber wad.
Making the wad smaller, or lowering the powder charge will sometimes cure the problem, but not always.
I have had smoothies that preferred two OP cards instead of a fiber wad, and then one, or two OS cards for best patterning.
And, of course, you're right again by saying "keep experimenting"....experimenting is indeed a learning process all its own!
Uncle Russ...