i usually patch a tube when i get a flat. there is usually one hole. i don't think this is unusual. although i've had the opportunity to patch multiple holes on occasion. so i'm not sure how it would be cost effective be to throw away a patch-able tube and buy a new tube at 500 times the price of a my patches and a little glue.

patches don't cost much, IME. this is what i buy at about $.02 a-piece... glue is extra.

and, it's been my experience that a patch that is put on correctly is stronger than the tube without the patch. i've proved this, much to my dismay, a time or two.