Who hates being upgraded, who insists on the same guide in the Serengeti, who will only fly first leg with a particular airline, who is back from Bhutan and ready to talk about the next trip, who proposed in Kyoto last spring, whose youngest has just gone up to university and now needs a different shape of half-term holiday. Every itinerary, every ground transfer, every check-in turns on detail that lives in designers' heads, on private notepads and in WhatsApp messages between ground handlers and the agency. When they move on, transfer or take a sabbatical, the agency cannot reach the intelligence that wins the next trip. So clients feel forgotten, new designers start from zero, and relationships that took decades to build leak away one resignation at a time.