This opinion is out of the Excel scope so if you want you can skip it Anyway, if you decided to keep reading I think that you are making this issue to complex, the first time you schedule the 200+ employee do it random (take the list of employee, make a RAND() column, copy and paste as value if not I will continue changing every time the sheet recalculates, order ascending) assign the spot in that order, and as a company policy every new employee goes to the bottom of the list. Keep it en the way you show you table.

Good luck!

Javier