I made some apple walnut pancakes from scratch this morning. There are certain ingredients I’m willing to guess on. The cinnamon and the honey won’t affect the structure and makeup of the pancakes. The baking powder and the flour, on the other hand, can make or break the batch. If not measured out precisely, you’ll end up with your pancakes either falling apart or too dry.
There are things that you must do “exactly” right. For example, you must show up for the train on time (unless you’re in Italy) and you must not lie when numbers are involved. With some other things, however, perfect is the enemy of good and you could save a lot of time by just eyeballing it.