The way this works is that my wife takes charge of booking, but can never find anything that completely satisfies her. She spends at least two hours online getting close to booking it each week, starting after Christmas, but the closer she gets the more worried she becomes that it's all about to fall apart, so the more cautious she becomes. Here's how it looks in graph form:
In practice the line approaches 100% asymptotically, so without any external forces the only way she crosses the line and actually books the holiday is if noise somehow propels her over it. Usually, though, she crosses it by getting me involved, so I can use my man shopping skills to say "that'll do" (woman shopping skills are "that'll do but we might find something that will do even better if we keep on looking").
Today, everything almost did fall apart when we noticed that the hotel we were going to book didn't say anything about guaranteeing we'd get a non-smoking room. My wife was staring down the barrel of having to choose a different hotel, which is a monumental task — the same order of magnitude as writing a programming language compiler, say. Fortunately, I was able to intercede by suggesting in my devil-may-care way that we check out one she'd rejected because she wasn't impressed by its name; amazingly, it fitted all her other criteria, so we booked it. Her ordeal is over until after Christmas, when it will start all over again.
Of course, the real excitement is only just beginning. We noticed that everyone's passports except mine expire in 10 days' time, and our flights to Italy are with British Airways...