One hears people mentioning that "AC V fare translates into LH V" etc.

My question is, is the translation consistent and uniform, i.e. is it the same for all itineraries? Or is it really case-dependent? In other words, can I count on the LH legs of my recently booked B fare will map into B? Or should I credit these to another FF program?

In the past, I have had experiences whereby my AC-issued latitude fare turned out to map into a non-flexible fare on BD. (But then that was not LH.)