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".