As a developer with a long experience, I will say this - for me such systems are useful in such directions:
1. generation of primitive but very voluminous code or similar information
2. Searching for specific errors in large projects (he is a bit more attentive than me

)
3. quick answer to a question that I can search for myself, but... I save time. But then I make sure I understand the topic thoroughly - because in the end I should have knowledge.
To get knowledge it's advisable to cross check the answers provided by ChatGPT or other AI Chat Bots. My personal experience with these AI chat bots is that at times the answers given by them needed fine tuning. There are online resources which are considered reliable (not every website has authentic information), it's better to check them also rather then solely relying on AI Chat Bots answers.
With code its different because you can easily figure correctness of code by checking whether your code is giving desired output or not.
Deep seek isn't really bad but I had a slight problem with it, after asking a question on something philosophical it started giving me but numerical results at first before give me the answers that I needed to know.... I kept wondering why that happened, I think it was a technical glitch or something but i don't think I've had such issues with chatgtp. I have been using ai bots for a while now and I think it's best to cross check them with Google or Wikipedia because somethings that they provide might not be accurate...but still, deepseek came out of the blue and plans on taking chatgtp out of business but I wonder why I'm not hearing much about it These days.