I do not agree with you frank, the schedule can be changed. This is done all the time.

In zwolle, as far as I remember, the saturday or sunday morning practice was cancelled. It could cause some trouble if the friday start-of-practice-time was changed. However, the end-of-practice-time could easily be prolonged.

The elite men could stop their practice at around 21.30 or something like that, without any problems, cause their race does not start saturday before 1 oclock anyway