Look up the grilling skill[0]. To make it even better, tell Claude to modify it to use the AskUserQuestion functionality. It's so much better than plan mode.

0. https://github.com/mattpocock/skills/blob/main/skills/produc...

Plan mode has become pointless since Opus 5 came out, they know when to switch between planning and execution now. But that iteration/discussion is still necessary unless you're building completely blind - the model cannot read your mind.

I've had it running 8h+ of non-stop optimizations, chasing a performance target, rewriting systems or building a series of prototypes for research. All it needs is a clear goal.