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In other videos Casey argues against the profile–fix–repeat workflow (I’m not saying that you necessarily meant this by measuring), instead arguing for estimating the theoretical maximum, then trying to get close enough to it. His argument is that the former might push you towards a local minimum without realising that you could do much better
When "Estimating the theoretical maximum" you're going to bring your assumptions to that estimate and so you're equally likely to get stuck in some local optimal point because you didn't see what else was possible, so that doesn't persuade me much. Worse, now it's a local optimal which might be entirely in your head. There is some space for this "Estimate the theoretical maximum" as a high level insight, if the softw…
That is you know the data is some size, and memory throughput is some rate, and clock cycles is some rate etc...
You are entirely correct about the line of thinking if your assumptions are down a different line of thinking such as algorithmic estimates though, where you might miss some better way of doing things.