Placing buffers between long journeys, international returns, or weather-dependent experiences. It makes routes resilient, but not blank.
First, design it as a soft day
Arrange a block, market, or optional museum instead of being stuck in a hotel all day. Even if nothing unexpected happens, it still has value.
Let it absorb useful surprises
Restaurant recommendations, exhibitions, or a slower morning can all be included in the itinerary because you don't have to wait every hour in advance.