I can understand your sentiment here. I guess my position is, when its dark, cold, or rainy (a good percentage of my communtes in the NW) I found that my patch jobs integrity, was often compromised by difficult conditions for repair. I can see how ideally, one could put on new tube, and then repair punctured tube later in the garage and rotate it in as your spare. I used to do this also. The last time I did it was on a tube I had repaired. Found out I had missed the small second snake bite hole. Repaired again. Found I had done a poor job and patch leaked. Repaired. Tube was good, installed. Still leaking, what the heck. Took it off, found I had then ripped a hole around the presta valve. Doh. Last puncture I repaired. Then again, at a present rate of one punture every four months, Im willing to buy the tubes.

That being said, when I was younger and a bit more frugal, I remember tubes when I was racing a bit that had 4 to five patches on them, and they gave me zero problems. I guess I lack both patience and manual dexterity now.