And here I thought my defacement of printed recipes by bracketing everything that goes together at each stage was just me. There are, well, maybe not dozens but at least two of us! Saves a lot of bowls when you know without further checking that you can, say, just dump the flour and sugar, butter and eggs into the big bowl without having to prepare separately because they're in the "1: big bowl" bracket.
Depends on what you’re doing. For best cookies, you want to cream the butter with the sugar, then add the eggs, and finally add the flour. If you’re interested and can find one, it’s worth taking a vegan baking class. You learn a lot about ingredient substitutions for baking, about what the different non-vegan ingredients are doing that you have to compensate for…and it does something that I’ve only recently started seeing happen in non-vegan baking recipes: it separates the wet ingredients from the dry ingredients.
That is, when baking, you can usually (again, exceptions for creaming the sugar in butter, etc.) take all of your dry ingredients and mix/sift them together, and then you pour your wet ingredients in a well you’ve made in the dry ingredients (these can also usually be mixed together).
No need to cakesplain, that was an example with three ingredients of the top of my head, very, very obviously the exact ingredients and bracket assignments vary depending on what you are making.
But for shortbread or fork biscuits those three could indeed all go in the bowl in one go (but that one admittedly doesn't really need a bracket because the recipe is "put in bowl, mix with hands, bake").