Planning is not easy.
Planning races is not as easy as most would think. Will I be ready? Isn't it too much? When to subscribe, knowing that places are limited?

You have to plan several months before for marathon races.
Obviously to have a good preparation, but some other parameters are significant for well-known races.
You have periods of prices to make sure that most of the people will not subscribe too late. So when you are student, you try to be in the first one. Often expensive enough that way! Moreover, when the race is really well-known, places are limited, so you have to be fast enough to be sure to have a place.

If everything goes well, my third marathon will be the Berlin marathon.