Having intermittently given in to the hype and tried whatever is supposedly latest and greatest, it without fail goes like this. I’ve even on occasion deceived myself into thinking I’ve finally hit on the right way to use these tools, only to realize in retrospect that under a complete accounting, the time spent to reach that productive mode of working in no way generalizes, so must be paid effectively every time.

This right here. Every time I talk to someone claiming 2-4x multipliers, after a few rounds of conversation they eventually admit "yeah you have to learn when to stop when it's no longer productive, you get a feel for when it's veering into wasting your time".

It can't be both. It can't be 2-4x multiplier _and_ be wasting your time to the extent that you have to "get a feel for when it has been wasting your time".