People may not think of this, but there is a science to finding the right balance between the main ingredient (usually some kind of meat) and the toppings. I call that the meat-to-condiment radio and in my estimation, the ideal ratio is as close to 1:1 as possible.
Take, for example, the perfectly balanced taste of the Big Mac. On the meat side, you have two all beef patties. On the condiment side you have special sauce, lettuce, cheese, ... well, you know how it goes. But what some people complain about on the Big Mac, that the meat patties are scrawny, is exactly the reason the sandwich tastes so good. If the meat were thicker, say, two quarter pound patties, then the meat-to-condiment ratio would be almost 2:1. Way off. Remember when McDonald's had the Double Big Mac and the Big Mac Jr.? According to Wikipedia, you can still find these at some U.S. locations. But why didn't they succeed nationwide? Because of a 2:1 or 1:2 ratio!
Photo courtesy of McDonald's
Ok, maybe this is all unscientific, but if science is largely observation, this is science of a sort. I challenge you to put together any list of popular fast food items (nationwide menu, not a local fad) that successfully strays from a 1:1 ratio. I suspect that'd be a short list. Staying with McDonald's for a second longer, even the Quarter Pounder with Cheese keeps the ratio intact with two slices of cheese, a few pickles, and generous squirts of ketchup, mustard and onions. Simply a scaled up version of the classic cheeseburger. (Yes, there is a Double Quarter Pounder - maybe that goes on the exception list.)
About the closest thing I can think of that has meat and toppings out of balance is upgrading a regular hot dog to a JUMBO all beef version. Typically I avoid this, because it usually arrives on the same bun with the same toppings, throwing the ratio all out of whack.
In the world of Mexican food, things aren't any different. The meat-to-condiment ratio is quite evenly balanced in offerings from Taco Bell, Del Taco, Chipotle, and the like. Even meatless items like a Taco Bell Bean Burrito balances out the beans with red sauce, cheese and onions in the right proportions.