I learned to use a scale for measuring flour when baking bread. I discovered that various flours (bread versus all purpose) are different weights for the same volume. And the gluten free flour I use is MUCH denser than either of those.
I have several sets of measuring cups. I think one of the cup measures is marked 240 ml, and another is marked 250. Really? Really?? For some cooking, eh, so what. For baking, it can be huge. So I use the red set when I make bread.
Some cooking is like jazz, lots of whatever, and anything goes. Some baking is like Bach, play it cleanly and precisely, or ... it isn't Bach.