Can You Simply Double a Baking Recipe

I often double recipes when baking cookies, cakes and breads. Recently I learned you are not supposed to double all of the ingredients across the board. For example, if making banana bread, you would double the flour, yet perhaps add less than double the egg and leavening? How about fat (butter/oil)? What other ingredients are you not supposed to exactly double? And, what are specific guidelines?

Sticking with the banana bread example, given the following ingredients -- 2 cups flour, 1 t soda, 2 eggs, 3/4 c sugar, 1/2 c oil, 1 c mashed banana, 1/2 t salt and 1 t vanilla -- which of these would you NOT double, and what would the adjustment be?

Thanks for solving this mystery!