I've had the agent tell me "this looks like it's going to be a very big change. it could take weeks." - and then I tell it to go ahead and it finishes in 5 minutes because in reality it just needs grep and sed.
One of my favorite things to do with AI is when a slow teammates says something is far too difficult (without explaining why) is to just... try it.
Used to do it by hand, which usually didn't take nearly as long as they said, and now with AI I can often one-shot these type of things, at least as a proof of concept.