Personally, I use it for various things in my writing, but mainly as an all-in-one tool rather than having it write for me.
First of all, I use it to translate, since English is not my primary language, but I always edit the text myself to choose words that could have more impact or better convey the main idea.
I also use it as a replacement for the Google search engine. ChatGPT at least gives me an answer with information instead of giving me a top 50 list of pages with the most SEO on the topic of my search. It might sometimes give incorrect information, but at least you'll have a base from which to search Google for something more specific on the exact topic.
I love using it for name suggestions, as it saves me a lot of time in finding a name that sounds appropriate for the context of the moment. You can ask for names by gender, nationality, or even culture, and you can request a list of about 20 names as many times as you want until you find a name you like.
And of course, my favorite is the command "Do an exhaustive analysis of the following text" and then inputting an entire chapter. This way, I can get an analysis of what a reader might notice in their reading and see how obvious or hidden those clues are to solve the mystery you are leaving. It’s like asking for feedback from your readers and using it as a test audience.
I don't use AI to write the chapter itself because no Artificial Intelligence is capable of producing the exact story I have planned in my head and in the exact way I want to write its scenes and choose the words. An AI has no way of consistently creating a long-term story with both recurring and unique characters that make sense. It has no way of knowing that the MC's martial arts master will betray him 30 chapters later, nor how to leave subtle clues about the future betrayal.
Oh, how to write that the nightmare or joke from five chapters ago now turns into an entire subplot that will forever change the future of that story. For an AI, there is only the present of the 10 seconds it is creating something to give you the answer to the request you made. There is no way to make it a "long-term intelligence" that plans things for the future.