Every mel has an interval during which it has to be repaired. You are right every operator has its own company policy. However if an ac is stationed for a significant amount of time , the defect should be tried to repair it else it is deferred, and then the ac is put under mel. Depending on the type of mel, each mel has an interval like A, B, C, D,
a= as specified in the mel
B= 3 days
C= 10 days
d= 120 days
I hoe this helps...