Some people have never once mentally rehearsed a picnic. The speech that goes wrong, the scan result, the conversation with the landlord — all of those get run in full, with dialogue, several times over. The picnic never gets a rehearsal at all.
That is not a failure of imagination. It is a very strong imagination pointed one way, by a system that believes it is doing you a favour by arriving there first.
The interesting part is that the machinery is identical. Whatever builds the disaster in that much detail is entirely capable of building the Tuesday in June, the flat with better light, the friend you have not met yet.
It has simply never been asked to.