I tried but it is not consistently 1 hour task down to 10 minutes. That is what I think most people experience, some tasks are really hit or miss.

For greenfield "make me a plain JS app that does X" yeah usually it is just able to do a small app that I describe in under 10 mins where I most likely would take far more than an hour to implement as well as just AI does.

For "hey I do have an app in framework X, implement feature that would take me less than 30 mins" - it might hit some issue and loop hanging on its own mistakes, hallucinate dependencies, hallucinate command line parameters and get stuck or just messing whole files. When such things happen I drop it do 'git reset --hard' and move on my own because trying to fix stuff by leading it usually ended up taking me hours fiddling with AI and not progressing on task.

But I also tried to make a greenfield apps with react and angular instead of just "plain JS" and that also mostly went bad getting stuck on some unsolvable issues that I would not have just using default templates/generators on my own.