Most nurses do not work set shifts they will work 3 weeks of 3 and one week of 4
It can be any shifts across the week
Regarding her doing 6 out of 8 would have been across 2 weeks
She would have done Fri Sat Sun Mon Tue Weds ..as she says in
@Tortoise quote above she would have done that to go on holiday without using her holiday entitlement ...she would then likely have 8 days off before back to work the following weekend
No holiday leave needed ..no time off in lieu...just by requesting what 3 days in a given week she wants to work