Japan's Labor Standards Act requires many companies to have a workflow for registering substitute holidays. This is for when an employee wishes to come into the office on a holiday, because if he/she does just that (i.e., works on a holiday), that day's payment must be increased by 35%. In order to keep payment to the usual rate, companies must have the employee set a substitute holiday in advance.
That said, HR management may be one of the least motivational office workflows for employees. They are often neglected and delayed. This could be improved. At least we could stop using a conventional paper-and-stamp system.
But will this workflow guarantee employees registering in advance? If it does 90% of the time, that means the employees of this company are exceptional people. Usually this isn't enough. There still is the problem of employees forgetting to start the process in the first place.
The easiest and fasted method is to share registered information with an electronic mailing list. Every time someone registers a substitute holiday, everyone is informed, and that's when someone else thinks, "Oh, right, I have to do that, too."