[rossdavidh]

All true, and I would also add a lesson from software design. Spaghetti code might, in some limited sense, be more efficient in some cases, but it is difficult to understand, therefore difficult to fix when something is wrong. Making things orderly, even from a top-down perspective, may be more important than being as efficient as possible, if you need to be able to understand what's happening in order to use (or fix) whatever it is.