having the task completed faster saves more energy than the long run.

That's assuming the task is a brief short load that actually ends. Race to idle when done right is more power efficient, but Intel isn't doing it right at the moment. Their lower end chips at the same tier can end up getting much better battery life than the higher end ones sheerly because they've capped their clock speeds to something reasonable. AMD does it well with zen 2 and zen 3, but zen 4 is starting to push performance over efficiency too trying to keep up. Every Intel laptop I've used in the last 5 years has gotten horrendous battery life. Doing the same task on an AMD machine gets me more or less the battery life I'd expect, and my M1 Macbook gets even better battery life than that (even running through emulation). There is 0 reason why my laptop from 2014 should get better battery life than my 2021 laptop doing the exact same task. The issue is Intel can't keep their clock speeds in their pants, and battery life suffers because of it.

All CPUs are binned. Mobile CPUs are binned for their low leakage current which is desirable for a laptop where battery life matters, and low leakage current means low idle power consumption.