senior dev, rust very recent onboarder : my personal experience is that LLM are super helpful at the very very beginning, because they show you the very common rust pattern, and help with the verbose syntax by reducing the amount of typing ( which isn't usually a problem, but in rust it can be).

Then once you start reaching for a bit more complex problems (like ffi, or building your own lib), llms are actually making waste time spitting nonsense.

However, once your patterns are back on track, and you start to know a bit better what you're doing, you can easily dismiss those bad advices, and immediately give the llm hints that will make them useful again.

At least that's my experience.