Last minutes can be interesting. Take now, for example. A friend who wasn't originally going to be able to do the British Universities Individual Sabre tommorrow has suddenly realised that he might be able to, so we're doing some last minute arranging on the transport. There's nothing like a sense of urgency to concentrate the mind.
Even so, it's usually better to avoid this sort of thing, particularly with anything important. One of my old law lecturers once pointed out that people do 90% of the work for their essays in the last 10% of the time, but still have to worry about them. If they did it in the first 10% of the time instead, they could have the rest of the time off.
Where this applies to writing is in the idea of getting the work done. The act of writing is wonderfully good fun, but so many people put it off almost indefinitely. 50 or 70, or however many thousand words of writing is intimidating, until you've written the first few thousand, and all you've got to worry about is what you're writing next.