Hrqls: The system is to be rewritten anyway, so I would not take it as a big issue. However, it can make problems if someone changes the weekend days because the system does not remember previous settings, of course.

I think the main problem is that the vacation system is already too complicated, as a result of attempts to satisfy all requests of improvements in the past (and some of them had been kind of ridiculous, so to speak). The system is planned to be a little easier in the future - for instance, it is not absolutely necessary to make the weekend days adjustable, so they will be probably set to Saturday and Sunday for everyone.