I used to schedule my travels early. Call me an organization freak but before arriving to my destination, I've already booked my tour guide, my transportation and my hotel. Aside from that, I've also planned itinerary up to the specific details such as what restaurants to visit, what food to order, what sights to see, my route, travel time, budget and more.
The problem I've encountered when planning so early and spending several days doing that for a trip that will happen way later is that it might get cancelled. There are various reasons that could make you back out on your trip such as a companion backing out despite or you're called in for emergency work.
Sometimes, you can try being spontaneous too and book late holidays. There are lots of online services now that make that possible and easier to do. So when you don't want to plan ahead and be disappointed, let's try late holiday booking and surprise ourselves.=)