Hi Maddy,
When you go to the Edit Mode of Org Structure and select one of the Org Unit, At top left you can find the Effective Date.
When you select the “End of the Assignment” for an employee, it sets the End Date of employee assignment to Org Unit to one day before the Effective Date of the org unit, with this the employee is no more assigned to this Org unit and then employee can be transferred to any other Org Unit (the setting of date will ensure there is no overlap of the assignment of employee to two org units).
An an employee can only be assigned to one organizational unit at a given point in time.
Regards,
Suman