Reminders can be set for a shift type (e.g. The same for all Night shifts) and changed for individual days if you need to, so really flexible.

To set up a reminder for a specific shift type:
– tap on the calendar icon in the top-right of the man screen
– tap on Set Reminders in the menu
– in the Reminders menu you can turn reminders off completely (for all shifts), set the reminder sound and change individual shift reminders
– choose the shift you want to change and tap on it
– Change the reminder time, the message that will show and even turn off reminders for a specific shift in here

All changes you make apply straight away