I reached my own productivity limit on several projects (in my case, I'm building a fully automated microscope that uses realtime computer vision to solve a number of longstanding problems with microscopes). As much as I'd want to write the code for it, I hit a wall when it came to debugging some particularly tricky issues- either I couldn't do it, or the time investment was too high.

I use Gemini/ChatGPT/Claude to do that work and it unblocked the enjoyable parts of the project while taking care of the tedium.

I also find LLMs help me learn faster because they can often take a paper and turn it into working code, which I find to be a very slow process.