|I guess that is what I am saying. What I suggest you do is to keep spare cartridges on site and run the cartridge until the quality deteriorates.|
If you are worried about wasting ink then don't pay attention to those levels.
For economical printing, consider a business class laser printer. The toner cartridges have larger capacity (2500 sheets or more) and do not dry out like ink tanks. IMO the only thing that inkjets are good for anymore is to print photos. Even then, you are better off using print services at Sam's club, Costco, pharmacy, etc.