When adding an entire raw egg at the same point in a recipe (not separating the yolk and white), what determines whether it should first be beaten, or dropped in whole? I've seen some recipes call for a beaten egg; others, specifically a meatloaf and a couple of cookie doughs, emphasize to not beat the egg before adding it.
The closest I found in here after an extensive search was this, which addresses why to add a beaten egg after the rest of the ingredients are mixed together, but doesn't explain why or when to beat it.
Why would a recipe say mix all ingredients, then add egg and mix again?
Other than the obvious mixing of yolk and white, how does beating it affect the proteins and other elements, and how do those effects impact other ingredients and cooking processes?