It's actually pretty well organised, since it's a big event, lots of things need to come together to be able to organise it in 48hrs time. Also the Dutch government has classified it as a so-called 'GRIP-1' type event, which means that all kinds of things have to be coordinated with the local & national government.

There is a great documentary (in Dutch) that shows what the foundation behind the Elfstedentocht has to go through every year to make sure they're ready in case the conditions are right to organise the race, not sure if it's available outside of NL:

https://www.npostart.nl/VPWON_1302414