Code made up of severally parts with inconsistently styles of coding and design is going to FUCK YOU UP in the middle and long terms unless you never again have to touch that code.

It's only faster if you're doing small enough projects that an LLM can generate the whole thing in one go (so, almost certainly, not working as professional at a level beyond junior) and it's something you will never have to maintain (i.e. prototyping).

Using an LLM is like giving the work to a large group of junior developers were each time you give them work it's a random one that picks up the task and you can't actually teach them: even when it works, what you get is riddled with bad practices and design errors that are not even consistently the same between tasks so when you piece the software together it's from the very start the kind of spaghetti mess you see in a project with lots of years in production which has been maintained by lots of different people who didn't even try to follow each others coding style plus since you can't teach them stuff like coding standards or design for extendability, it will always be just as fucked up as day one.