With that amount of experience I imagine GPT is explaining stuff you already know and is thus saving you time.
For something completely novel, or as someone with little experience, it’s going to be harder to get that kind of result in terms of understanding the requirements, writing the prompt, and comprehending the output.
It's something I have little experience with, or at least, it's not in the domain of skills I've used in years and certainly not with the type of tooling I'm using. At a high level I do have good knowledge of what I'm trying to build and how it should operate though. Like I said, it probably would take me about a week unassisted, mostly due to a fair amount of reading and experimentation.
