If there are three people, A, B and C, then A (Monday), B (Tuesday) and C (Wednesday) should be on duty. . .
So, this line goes on, or that day. If it's the same day, it's necessary to check whether this person has queued up a few days ago.
First of all, there is a list of people, which records many people. rota
Then the front desk shows who is on duty today and who is on duty in the next few days.
Just process it in the background. Black and simple.