They last much longer in storage /without printing because toner is a powder, so it can't dry out. The print head of an inkjet printer (part of the cartridge) will dry out if you don't use it for a few weeks.

Still the exact same printer my family has been using for the past 10 years after our old Inkjet kicked the bucket a measly 3 months after it was born. And it has seen some stuff, including being dropped at least twice, plastic film in the paper compartment, coffee-stained (for aged effect) paper, and even a x-acto knife blade that somehow ended up in there.