It's not an automated process (at least in my case). I primarily use Codex so I will do the initial pass with 5.3 or 5.4 xhigh and then cleanup with spark on medium or low.

Spark is great for this kind of cleanup work because the feedback loop is so tight compared to just about anything else. It's quite hampered by a very small context window but in the context of cleanup/refactoring that's more of a feature than a bug IMHO.

My suggestion for folks that want to do this is make sure you keep reasoning low. The cleanup should be very much human directed and derived from your "taste", at that point you don't want the model to think at all and just blindly do what you tell it to. You want reasoning to be just high enough so it doesn't eff up the code in the process.