I few years ago I had a rash of flats. Unable to determine the exact cause.... I replaced the tires and bought new "thorn-proof" tubes.

OK.. I live and ride in the Midwest... nowhere near a thorn that could damage my tubes. But I figured those super thick tubes had to be of some help. Of course they do add weight and the tubes are too large to stuff into a saddle bag.... so I carried a "normal" tube as a spare. But neither of those tubes have ever went flat. That bike in now my rain/foul weather bike.

I got a new Trek last July and within the first 1000 miles (stock tubes) I'd had a flat. I haven't switched the Trek over to thorn-proof tubes and because of the added [wheel] weight I may not... unless I have a rash of flats. But I do know the thorn-proof tubes are a solution.