Not read that before but I'm pleased that they work the way I thought they did. I've never worn one for a long period because they hurt my delicate face but I wouldn't expect to see any consumption at all at normal cabin altitudes.
I've never understood why the cabin pressure warning is set so high. Why not warn the crew at an earlier stage of an abnormal cabin pressure? I'd quite like a gentle nudge at 7000' cabin alt rather than 3000 feet later.. Can't be that difficult to sort an algorithm that accommodates high elevation airports but flags up a problem when the cabin starts climbing off schedule.
The lack of replies probably gives an indication of the number of crew that wear one in the cruise..