We considered optimizing registration of substitute holidays with "The Bottleneck of Employees Working on Holidays Must Be Making Them Submit Requests Beforehand." But let's think about this a little more.
The below sample is for a company that holds a meeting to decide which employee will work on what holiday. The task for registering substitute holidays is automatically sent to each employee on the 25th of each month, so that he/she can send it in for the following month.
Of course, an employee may need to start this workflow him/herself in the middle of the month, for an additional workday. And if HR wants to make sure the employee came into the office as was planned, and took that substitute holiday as planned, the below workflow may be better.