How do you make palace-stored information last instead of fading?

Review by re-walking the palace on a spaced schedule — soon after learning, then at growing intervals.

A palace makes information easy to lay down, but like any memory it still decays without reinforcement. Walk the route again a few minutes later, then hours, then a day, then a few days — spaced repetition applied to the journey. Each successful walk strengthens the images and the links. For a one-off need (a speech tonight) a couple of reviews suffice; for durable knowledge, keep spacing the reviews out.

Tip: This is the same principle this whole app runs on — retrieval at expanding intervals.