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Never seen the point, although plenty of people have done it. If you want to write, write FFS. Why wait till November? If you need a bit longer than a month to get it right then take it.
The point is, the inertia+suggestability of human nature. A lot of people would like to have a stab at writing a novel but never get round to it, or don't see it through to a conclusion. If someone else suggests you do a thing, within a set timetable, that other people are doing too, some people will seize the idea and run with it, and maybe derive pleasure from it and achieve something. Someone else (e.g. yourself) won't. Each to their own.
The process is similar to the London Marathon. If the LM people hadn't bothered to organise it all those years ago, hundreds of thousands of people would never have run a marathon who, instead, have. Often we do things because other people give us a vehicle within which to do them.