Heavy agree. For high level architecture work, refactors, or any other high int problems, I use Fable and Astra. Whichever one starts the work, the other reviews the work / makes suggestions.

There's a trend on twitter going around telling you to paste the following into your agent, and it's the kind of work I go straight to fable+astra for:

    Find all of the implicit state machines in my app. Make recommendations for changes that will elevate all three: the user experience (UX), developer experience (DX), and agent experience (AX) always, without breaking anything.

Re the twitter trend prompt, one thing I added to mine that improved the outcome was this blurb:

    Look at the code pathways for anything you find. Look through the git history for each one. Understand why code was written the way it was. Revisit each hypothesis and give me a full plan again after you're done.