I got that, but my point was, why not just carry a pump. I understand the convenience of a C02 inflator. They can be very easy to carry when on a road bike or other bike with limited carry options, but for a commuter bike a pump is easy to carry, and if you get a good pump, inflation is easy.

All that being said, if you carry a C02 inflator, you are right, multiple cartridges is the smart move.