How often are you going into new projects and spending up to an hour on set up? I'm really just asking to get a sense of what "Generally" means here.
I do it with every project I go into. First step is setting up the documentation so that the agent can navigate it quickly, knows the idioms, knows the test gating procedure, design principles, coding standards, testing policies, etc.
Once that's set up, I spend time laying out the planning for whatever feature or fix is being worked on. For fixes the agent is pretty quick and usually needs little guidance. For new features it's best to have more of a hand on the tiller.