How can you say clubs lose money regarding the 28 day rule?
I'd have thought that my post was quite clear.
But here's a slightly longer version for the hard of understanding:
If a club has fixed slots for booking its aircraft and instructors, which sounds to me like a reasonable way of avoiding complete chaos, then if the instructor and aircraft are being used for a check ride and bringing in 15 minutes money they can not during the same slot be used for a full lesson and bring in a full hour's money.
An hour's hire is more money than a single circuit.
The club thus loses 45 minutes money by allowing a punter to book an aircraft and instructor for a one circuit currency flight.