I've tried to use ChatGPT (and Bard) for various day-to-day things, and honestly I have not found much of a place to fit them where they actually are helpful enough to actually incorporate them. I haven't tried the paid tier GPT-4 models, maybe those would actually be more useful, but the free tier has been less than impressive for me.
For writing tasks, I haven't been able to use it effectively for most tasks. It does fine on creative tasks but it doesn't really produce anything impressive enough to be middleware for writing. It's fine for writing emails and stuff though, just that I am not writing enough emails in a day for it to be a notable part of my workflow. I also don't like using it for technical writing. Expanding or rewording on technical content often leads to strange sentences, mostly because it tries to synonimize technical words that ideally shouldn't be tampered with in such a corpus... Maybe some better prompts would help with this, but I haven't had the chance to experiment more
I also tried it as a brainstorming tool, to try and pull out new ideas or to hold "discussions" so to speak. Again, it isn't bad at it, but often reverts to generic responses or occasionally repeats itself and it's just not efficient nor consistent enough for being a regular tool for this
The one thing that these models are exceptionally good at, however, is giving great overviews and explanations on concepts. It probably won't help you much if you are asking highly detailed, convoluted and specific things but they are amazing at "skimming" information. Like another user mentioned, it's good for obtaining domain knowledge on topics you're unfamiliar with. Kind of like a headstart for your learning process. I've found it very useful to get a general notion of "where to look" when I want to learn something new or run into hurdles on a project.