Using both whipped egg whites and egg yolks vs whipped egg whites only? Would you get more leavening if you used both whipped egg whites and egg yolks and folded them into a batter (pancake batter,for example)compared to using whipped egg whites only, and would it make a noticeable difference? If yes, then why is it more common to use just the whites?
Whipping egg whites is usually done to make a batter lighter and fluffier. In such a case, adding in egg yolks will likely make the batter denser and less fluffy.
On the other hand, if the recipe has substituted  egg white for egg in order to make a recipe healthier by reducing fat content, you can revert to using whole eggs (1 for every 2 egg whites). The texture will still be different, but that might be what you want.