3 month regime

[Orangesandlemons77]

• Three-monthly cyclical regimen — oestrogen is taken daily and progestogen is given for 14 days every 13 weeks.
• A monthly regimen produces monthly bleeding whilst a 3-monthly regimen produces a bleed every 3 months.

From the Nice guidelines, can anyone explain how this works in practice please? Thanks

I'm confused about the 13 weeks, would it not be 12 weeks / 3 months, with the progesterone being taken in the last 2 weeks of the 12? Or is week 13 the bleed week so the it goes back to week 1 again?