Deck joist cantilever distance with multiple intermediate supports
The cantilever can't be too long for two reasons.  One you want it to be stiff, so you don't have a diving board effect on the cantilevered part.  Two, it can't be so long that weight on the cantilever part has a see-saw effect and lifts the other part of the deck off its supports.  

I think you could certainly make the argument that you could cantilever (AZ/4) as long as the joist is sized to span AZ.  (According to the cantilever joist span tables.)  If that is the case, the supporting beam at B is not required and I see no reason to shorten the cantilever because you have an extra support.  

Otherwise I think you'd need to have an engineer's stamp on the plans to use something between AB and AZ, up to one-fourth of the maximum span of the joist per the table.