You mean why not work myself instead of the agent? That'd be because for me it's been working great, and so it does make sense. In the scenarios it doesn't, I do indeed just fall back to manual work. A lot of those scenarios are obvious too, so not too many wasted runs to speak of either.

I did give up on cheaper models, they required constant babysitting, and in those cases yes, the benefits indeed evaporated. The expensive models have been genuinely working wonders though, and were still able to justify themselves economically plenty, at least by my own measurements.

I think there's also one underappreciated and indirect way agents help with productivity: they counteract the attention span collapse of the past years. By being addictive themselves, they keep you engaged, and being engaged means being productive. Not even asking an agent to check something out feels too rich, and once you've asked, you're already one foot into the flow.

There's also definitely been some honeymoon effect going on for me, where I dived into more work more readily, just to see if the agent can figure things out on its own.