For instance, I have been going back and forth with /grill-me in plan mode for 4 hours now.
Sometimes when it asks me a question, I ask one back.
Sometimes it makes a suggestion and I'll ask, "But what is the right way to do this". All of a sudden the suggestion changes dramatically.
Sometimes I make a decision later that conflicts with something I said earlier. So I tell it to roll back to that point and continue from there.
You can do anything you want in plan mode. There are no rules.