I only really know about mtb tires; glass and wire rarely seem to puncture a tire straight away but has to work its way in to the tire and then holes the inner tube. I usually go over my tires once every couple of months and its amazing how much glass you can actually cut out of them.

Thorns are the only thing bar large objects that will go straight through a mtb tire. The only two things that completely wrote tires off was riding over half a broken bottle in the dark that was standing up and the other time a drill bit that was welded through a piece of sheet metal so the bit itself was pointing upwards, (I still have that somewhere, almost like it was made for the purpose of causing a puncture).

I wonder also if riding with mtb tires makes you subconsciously more gung-ho when riding over stuff? Also due to the knobbly bits on mtb tires its often harder to see stuff like goatheads sticky out of the tires maybe?

When I lived in the UK late autumn was a bad time due to hedgerows being trimmed by the farmers I would average one puncture aweek and that was with tire liners in place due to the tons of hawthorns and blackthorns lying around.