Except, unfortunately, they encourage people to keep optimizing that one issue even when it's long past being the bottleneck. Equally, what's a bottleneck in on

Except, unfortunately, they encourage people to keep optimizing that one issue even when it's long past being the bottleneck. Equally, what's a bottleneck in one implementation might not be in another. Having the entire real-world case means you have to optimize for the actual case, and not just implement what was at one time the bottleneck in one implementation as quick as possible.