I don't use llm, but I have my own "think" tool (with MUCH less support than llm, it just calls openai + some special prompt I have set) and what I use it for is when I need to call an llm from a script.

Most recently I wanted a script that could produce word lists from a dictionary of 180k words given a query, like "is this an animal?" The script breaks the dictionary up into chunks of size N (asking "which of these words is an animal? respond with just the list of words that match, or NONE if none, and nothing else"), makes M parallel "think" queries, and aggregates the results in an output text file.

I had Claude Code do it, and even though I'm _already_ talking to an LLM, it's not a task that I trust an LLM to do without breaking the word list up into much smaller chunks and making loads of requests.