Its not insurance the standard club insurance is only done by 2 companys.
When I go home I take an aircraft out solo for 3 circuits and I am over 90 days never mind 28. I don't need to I might add for teaching I just prefer to anyway in case I have to sort a landing out its more to do with the weight of the controls than anything else. I checked with the insurance company and they are fine with it.
We have variable time limits but usually the punter wants to go up anyway even if you can say they can take it. Maybe its reverse physcology or we don't have any knobs as instructors and an hour/3 circuits with an instructor is seen as a fun thing to do and not a PIA. Whenever I do one of these the punter logs PIC anyway maybe that stops the mind set that its just done to fleece them.