Originally Posted by
abgd
One of the particular problems with 28 day cycle is that if you fly one Saturday, then can't fly until Sunday in 4 weeks' time, then you have to find an instructor...
... which is why my club changed, after years of nagging from customers, from 21 days (with the Saturday/Sunday problem) to 22 days.
You might try persuading a club on 28 days to move to 29.