Cotton is superbly biodegradable with or without the presence of oxygen. The composition of the lubricant will determine the rate, but.it WILL eventually decompose. Whether the level of decomposition effects your shooting may be dependent on your particular shooting standard, but I personally would consider pre-lubed patches the equivalent of a compost pile after a season or so and not use them for serious work. I have had dry un-lubed patches that are stored in a sealed, dry package last 20+ years. IMO.