I always pump before my rides so the CO2 issue is pretty much null for me which may be why I say rubbish to it but I still haven't seen a true flat overnight with CO2.

Why pump before every ride? It is kind like how as a kid our parents make us brush every night, it is good for you yes but it also becomes habit. It just makes sense to check with a tire pressure valve every ride so I don't have to deal with pinch flat which pisses me off more than any other flat because it is so easily avoided. I cannot even count the number of times my tire feels okay to the touch but I put the pressure valve on it and it is only 80-90 PSI. Also I get so scatter brained some days I wouldn't remember if I did put more air last ride, two rides, last year. LOL. My 2 cents threadjack.