A couple of years ago I bought a color laser printer. I used it fairly often and after 6 months the out of toner warning came on and I dutifully changed the toner.
About 5 months ago I discovered an override button which allows the printer to keep printing while you obtain a new cartridge. It is now 5 months later and the printer is still going! Print quality is fine and the new cartridge is still sitting on the shelf. That is almost double the life. Hmmm, I think HP might have been ripping me off.