Not filling every hour
There is an art to not filling every hour. Sitting to watch a square, missing a bus, and finding another way belong to the trip as much as the place you were going. If the day is booked end to end, you travel beside the place, not inside it.
Leave a block with no plan, even if it is an hour after lunch. That gap is where the thing you later tell usually appears. Not because it is spectacular, but because you had time to see it.