Hours question

Everything is on a fixed week. From 00 00 sun night/mon morning
You can do 3 15 hours hour shifts a week rest of shifts have be 13 hours…
I keep hearing at times it’s 3 x15 hours over a 2 week period. Ie you do 3 this week next week can’t do any. Or 1 this week 2 next week… altough don’t think this is the law unless others prove me wrong.

Why need a diary so can quickly see how many hours you’ve done.
Don’t forget time starts as soon as card goes in so if you work 13 hrs 1 Min. Technailly it’s classed as a 15 hour shift…
If your on 4 on 4 off your days are sat sun Mon Tue. I’m guessing you could do 15 hours all 4 days as it over laps 2 weeks.? Don’t know on that one.

Best advice will give if office ever ask you how many hours you have left just tell them 13. As soon as you say 15 there plan you a 15 hour shift.
Just keep saying 13.