Using Shifts for Labour Recording V8.03.406a

On Mon - Thurs we run a day shift from 6:00am - 3:00pm with 1 hour for lunch.
On Fri our day shift runs from 5:00am - 1:00pm with no lunch break.
On Sat our day shift runs from 8:00am - 12:00pm with no lunch break.

We have defined each of these shifts in Vantage OK and have associated the Mon - Thurs shift with each shop floor employee.
This works fine Mon - Thurs but on Fri and Sat we are relying on the shop floor user to remember to select the correct shift which most of them forget to do. This then causes problems with our time and attendance reporting to payroll because the users are showing up as logging on early and finishing early on Fri and Sat. Unfortunately the shift is not associated with a calendar so cannot be controlled that way.

How do other clients manage this?