patch kits are cheap, small and light. no reason to not have one. I had a pinch flat last Saturday. Threw in a new tube and pumped it up only to have it blow out (sounded like a gun shot). Borrowed a tube from a fellow rider but the short stem length didn't work with my aero wheels. Good thing I had a park kit on me. Found the snake bite on the 1st tube, patched it up and was back on the road in no time.

they are also nice to help out fellow stranded cyclists with when you don't want to give away a tube.