A flat after hitting something hard, like the concrete edge of a bridge approach where the asphalt is quite a bit lower or the edge of a pothole, might be a pinch flat. That means you either have to put more air pressure in your tires or you have to quit hitting those things. Pinch flats may or may not produce the double puncture that has gotten them the name of snake bite.

I don't pride myself on patching tubes. I don't flat often enough to stay in good practice. The adhesive is usually dried out by then and other things. So I just put a new tube in. Besides, I have too many uses for old tubes around the house and shop.