Laplacian Pyramid - Blending Images Method- What is the meaning of layers (many vs few)

Its more of a theoretical question.

When I get 2 images and I want to blend them using the Laplacian Pyramid method I have been using a different number of layers each time and I can't see any big different.

I have been using it on 2 different focus images of the same scene and while i use a large number of layers there is a tiny better focus on the final image.

but what is the true meaning of using a lot of layers ? mathematical wise... or any wise...

thank you, Despairy