Is it possible to get a glaze shine on cordovan? I know that the mfg. recommend only occasional, light polishing.
Yes, but it will not get a mirror-like finish like calfskin. Still, it looks very nice. I polish my burgundy shoes with black polish.
I don't think there's anything wrong with polishing shell more often that the manufacturer recommends. The only downside I can see is the wax buildup in the creases that "flexes out" as you wear the shoes. I just brush it out before I leave for work, and do it again when I arrive at work.