I would not class eating TWO cinnamon buns back to back as a "snack", but rather "a disgusting pig-out". Am I sheltered?

No, I think you have your head on right.

I used to eat a lot of candy, but I never considered eating more than a handful of anything a "snack".

That said, what do you call it when you eat something that isn't a meal? I don't think most people have any word other than "snack" without resorting to things that sound like insults, like "pig out". And it's really hard for most people to insult themselves.

I’m not a big fan of sugar so I wouldn’t be able to eat a whole cinnamon roll, let alone two. But if I’m doing a big hike I’ll have no problem demolishing a whole tub of rillettes, which must be at least 1000kcal

Maybe you're just not in a location where that sort of eating is common. Like the American south or midwest.