My only experience in >24h agents is with economically sane models (one of GLM5.2, 5.3-flash for orchestration, DSV4-flash for implementation, and glm5.3|sol|kimi3 agents + subagents reviewing at the end)
Over 24h my token spend is <30$. Excluding tokens for review it's <10$. With the absurdly gigantic subscription subsidies and a reasonable workflow I suspect one could run parallel agents.
I'm not sure what the point would be though unless working on some kind of optimization problem -- it takes me days to review <24h of the agent's output. It's almost always near enough to correct to be shippable; though I do give it feedback and iterate until it's better than the code I would have written.
It only really makes sense for problems that are complex and require iterations that don't themselves require much review. E.g. if you want find, PoC, and patch bugs, the output can be reviewed without reading all the traces. Or if you want to write a custom tool that does some job using local LLMs, assembling that pipeline, tuning the prompts, etc takes a long time but reading the final tests + eval data + code is enough to get a lot of confidence that it works right. Model checkers can help too, for example I wanted multi-sink Bluetooth audio support in Gnome for my kids so I hooked the hardware up and robo-coded the core logic specifically to be checkable with Kani.
>don't themselves require much review
I'm still wary of any unreviewed code - though my area of work is not tolerant of defects.
Agree on targets / verifiable indications of progress or success being a prerequisite for this being useful - although that covers quite a lot of SWE work.
This sounds like more work than just writing the code yourself. You'll say it isn't. I don't believe you.
That is an incorrect presumption - I think it's plausible this is more work; it's certainly far more taxing.
I'm at a point in my career where a small minority of my time is coding. The AIs can do in a day what would have taken me a week uninterrupted with acceptable (in some cases inferior prior to human feedback--but in some cases superior!) quality.
As I do not have 10 let alone 40 hours per week to devote to coding I think it increases the amount of high quality work product I can create with a given time investment. As I review it I merge small independent units and decompose the work.
All that is to say I don't really like it - but I suspect for most *well defined* coding tasks human produced code from highly experienced engineers will largely cease to exist in the next year -- getting cheap/relatively horrible models to produce good code is now straightforward.
OTOH I never use AI for any human facing communication outside of making my writing shorter. IMO AI slop "documents" are almost certainly a drag on organizational productivity.