I have always believed this. I hope I can someday learn why.
On another note, my HP C8100 All In One Printer quit working. It kept spitting out blank pages each time we tried to print. The ink levels were fine with the exception of the MAGENTA cartridge which was out. It still would not allow me to print in black. (My printer has individual color cartridges) I replaced the magenta and then switched out the black one for another new one. It now works fine again. I sure hope that brand new black one I replaced will work someday. I just broke it out of the package but I think it couldn't "read" it. I wonder if some of the printer updates we run block out certain ink cartridge codes if they are older. I guess that would be a reason to not stock up on them if it's true.
Why is it that printers just don't seem to last long? So thankful to have it working again!