No matter how good the spiel around the scrubber monitoring is, I'd be particularly careful not to believe in it too much. Certainly in terms of when to change the scrubber.
I don't scrimp on scrubber changes at all. The temp-stick (the kind that knuckle dragging, seahorse trim, Christmas tree dangly, AP Inspo divers like me have) is most useful for me to show that the scrubber is acting as it should be. No channeling etc.