It takes significantly less than a second to turn a screw once. A couple orders of magnitude less actually, to give it some relation to the computer question.

Which really just demonstrates the point, I think. At some point things are "fast enough" that it just doesn't matter. We've reached that point with computers. Unless you are working in a niche field that needs serious compute, the sources of performance problems are almost never going to arise from issues like trying to execute too many add instructions in a given period. The delays will come from things that are significantly harder to see - network, database, or program architecture + runtime.

> At some point things are "fast enough" that it just doesn't matter.

...and 640K will be enough for everyone!

The carpenter may simply know that turning the screw is imperceptibly instant in his experience, and that if the bookshelf isn't getting built quickly, the bottleneck is virtually never because he's waiting on screws to be turned. He's going to have to make a trip to the store anyway so he isn't concerned with whether turning the screw requires a tenth or a thousandth of a second.

He's more focused on the design and craftsmanship of the bookshelf, because he's built many excellent bookshelves to industry standard effectiveness in the past and measuring the number of screws he can turn in a second hasn't been relevant to the work.

If he is good, he can reason about it on the spot. If he can't, I very much doubt that he can design anything excellent. That requires critical thinking to understand what it is being used for, what is good, and importantly what solutions are unsuitable for the problem he is trying to solve.

Sure, although I was addressing the parent comment, and more specifically, "knows it in his bones."