More likely the improvement is minimal and it’s recovered across many sessions. But still, the net result is supposed to be positive by a large margin.

It's a bit like trying to write the perfect piece of software. Some people wouldn't bother with the effort and would instead use something written by others, I mean we all do that to some extent.

It comes down to, why do anything?

If you do want to make anything or do anything, it's never a wasted effort, even though you'll never succeed in doing that perfectly.

Over a 5 year time frame something that saves one second per day is worth about half an hour of time.

Something that saves 5 seconds 20 times a day is worth 50 hours of work.

Over 20 years its worth 2 hours and 200 hours respectively. It's probably pretty easy to find optimizations in any environment that are trivially a positive investment of what you correctly note is your most valuable asset.

You can't code effectively if you don't spend time optimizing your workflow, and there's no single thing as important for that as the environment you're actually typing the code into.