Hey Sharp,
I've pulled pieces of glass and wire out at least four time a year but never a flat.
I ride through urban crap everyday.


Maybe consider tire liners? I use them and feel that since they aren't laminated within the tire, and are free to move, the debris won't reach the tube and cause a flat.
I initially bought them for thorns but they stopped a nail from causing a flat in town.

It's worked for me for about 5 flat free years. (schwalbe regular marathons and Mr. tuffy liners.)

good luck.