I've just began pursuing my education in baking and culinary management about a year ago so my answer may not be the most technically eloquent, but from what I've learned so far, understanding what each ingredient does for a recipe and personal experience with the art is the key to knowing how to properly balance your recipes. For example, when it comes to working with cakes, there are 4 main ingredient functions, Tougheners, Tenderizers, Moisteners and Dryers. (You also have to pay attention to what type of flour you use, because different flours build different levels of gluten based on how much protien is in the flour.) Tougheners include: Flour and Eggs. Tenderizers: Sugars, Fats and Chemical Leaveners. Moisteners: Water, Milk, Syrups and Eggs. Dryers: Flours and Starches, Cocoa and Milk Solids.
You also need to take into account that some ingredients have 2 purposes, Eggs for example act as a toughener because they contain protien, however, they contain fat as well which acts as a tenderizer.
Educating yourself on how to properly balance recipes, learning how certain ingredients interact and support one another and a little trial and error are all paramount to mastering and perfecting your recipes.

Hope my rant was helpful!

Have you checked out Michael Ruhlman's ratios? He has a book that spells out the ratios for different types of foods, and he can sell you a handy chart.
You can see the chart here. I've not read the book, nor used the chart, but I think it might give you what you are looking for.

I've been baking for decades and the best thing to do is find recipes that weight ingredients, after that it all boils down to simple maths.
For example, in a pound cake, you're supposed to get the same weight for all the ingredients (eggs should weight the same as the flour, same as the sugar and same as the butter), no matter what the technique is (cream the butter with sugar, or melt the butter and add to the mix of eggs+ sugar, whip the egg whites or not, add baking powder or not, etc).

So if you have 2 recipes for a pound cake asking for different # of eggs, you need to look if the recipe with 6 eggs has more flour, butter and sugar than the 4 eggs one. If not, it's likely your 6 eggs recipes might come out too wet, will take longer to bake, etc. 6 eggs sounds like a lot of eggs for a pound cake recipe to me, BTW.

Now for leavening agents usually it's either baking powder, or baking soda + something else, or whipped egg whites. If a recipe call for whipped egg whites, adding baking powder is often unnecessary, so just a teeny weeny bit can be added for some extra oomph (think 1 teaspoon).
The more baking powder there will be in a recipe the more your pastry will rise and become fluffy. If there's too much of it your batter may very well erupt in a sickening mass on the bottom of your oven. At best your cake will have some metallic taste. At worse it might turn too tough. and will look strange.

You need to look at the other ingredient quantities for your recipe, and try to figure out if the recipe makes sense. For example 3 tablespoons baking powder for just 1 cup flour is likely too much leavening agent for most recipes.

I don't know if what I say makes more sense... but it's really a question of balancing proportions. If you make a tart dough for example, the weight of the butter should always be 1/2 the weight of the flour. More and it will be too soft and the dough will be too sticky, less and it will be too dry and will break.

Thanks! These are really helpful comments!

I second BakeWise. This book will teach everything you'll ever need to know!

I recently took a commercial baking course and we were taught BAKER'S PERCENTAGE, Ratios and formulas together with FUNCTION of INGREDIENTS.

With these in hand, you will be able to compare and contrast different recipes and predict the outcome of certain recipes if you were to change the "formulation".

All recipes must be converted first into percentages relative to the main ingredient which is flour to do this properly.