[paul.fr]

will repeated opening and closing of the bag containing a loaf of bread, increase the rate of mould growth?

[JimBob]

It lets more spores in as well as spreading around those few spores from the mold's fruiting bodies already on the bread. So I have a feeling the answer is "Yes"

Of course, I am not a mycologist. Is there a mycologist in the house?

[Jimbob12321]

By opening the bag more times, it would allow more moisture in allowing the spores of mold to multiply, and as more moisture is let in the faster the multiplication.