Standard respirator hygiene includes sealing the entire respirator in a ziplock bag and keeping it wiped clean with antiseptic towelettes between uses. If you do this, your cartridges will last just fine since they won't be getting exposed to anything that "activates the charcoal".
There are also pre-filters available that keep small particles from clogging the actual cartridges. These snap over the outside of the cartridges.
Cartridges are made for protection against specific compound types, such as VOC's. MSDS system was created so a person could identify the specific personal protection recommended for a given material. You may wish to compare information to see what you are getting and if it meets your needs.
For instance, protection from burnt PVC material that puts off clorine is a whole order of magnitude different than protection from organic solvent or heavy metal gasses.