A couple more things that have cropped up very recently that can catch you out if your unprepared.
Most of the cyclists in my club do not fix punctured inner tubes but dump them when they get home but me being a Yorkshireman take them off them to take home to fix.
Very recently one rider had a blow out downhill, on examining the tube at home, I repaired one hole that I had found, but then found another, repaired that one and then found another which I also repaired, but it still would not pump up. On examining the tube closer, I found another 5 holes and there was probably more as I gave up looking. As the cost of the patches would probably be worth more than the inner tube I dumped it.
Thinking about it later, the puncture happened downhill at speed, so the rider could not slow down quickly and that probably caused all the holes, pinch punctures. The lessons in this scenario is, if punctured slow down quick and stop to prevent more damage (I have a tendency to roll on a good few yards more to a good spot to effect repairs, but not no more now), always ensure you do have enough patches in your kit and always ensure that you do have a spare or more innertubes for that multiple puncture that is unrepearable.
Another incident this weekend, rider punctured, I took the tube home and found I could not repair it very easily. I tried two different rubber solutions and two different types of patches but none would stick to the tube, even after a couple of hours the patch would just peel off or blow off, even gave the tube a good roughing up with sandpaper but that made no difference. In the end I did manage to patch it but I had left it overnight for it to bond, out on the road it would be a problem unless you have a spare or it is your last spare that has punctured.
Lesson here is if possible test the tube out and stick to tubes that you know will take a patch. The tube was a Continental race 28, sadly I have just bough 3 new Continental tubes but a different pattern so I shall have to try a small patch on one to see if they are OK now.