Michael,
My intuition is that you may be on to something. I use my 4880 in spurts, using an inordinate amount of ink just fort nozzle checks and cleaning. The VLM is always ahead of all the others by 25% or so. Unfortunately I have not recorded any of my exact ink issues, or gone though 4 sets of ink yet. If the printer sits, it's always the yellow, or one of the magenta patches that has a clogged head, the printer may be using more of one color in the cleaning/shutdown process to try and compensate. Again. it's more of an impression than an objective measurement.
Dave