Canon Pixma Pro 9000 Mark II Question

tas

I have done it both ways. I use the Pro 9000. The printer will stop printing at some time and you will need to replace it before printing will resume. This can happen in the middle of a print.
Don't know if this happens to protect the print head?
I would print as long as possible on an ink tank.

I basically print till it won't let me print anymore. The software will warn you, warn you, then will finally not let you print. When you have to change out the cartridge, there will always be some stuff left in the "foamy" area, but that's normal.