I don't do a lot of baking, but when I do, I measure, sift, weigh... and have still had some less than sufsccessuly outcomes? Finally realized problem was probably with eggs... al ALwAYS buy jumbos (from littl Asia market) and every recipe calls for large. I'm sure that throws a cake recipe off significantly... 3 jumbos have to be at least 4 large eggs?!?
For recipes other than baking... anything goes. Today I looked up a recipe for chicken caccatorie. It didn't call for black olives... but I had them and knew they'd work. If it's not baking... pretty much anything goes. If I like an ingredient and think it'll go with others... it's in there.
How about you?