Did you check the 10.8 or the 4.3 readings by doing a retest?
Yes, both, first thing I did, and on alternate hands too . These two extreme figures were within <1 of the retests, so I took them as being “correct”. And yes, always clean fingers/hands. It was just this extremis swing that I’ve not been aware of before, over just three hours.
Since September 2019 I’ve executed some 900 tests and recognise the need for retesting, if not just for veracity, but my own sanity. But thanks for asking .
JohnEGreen’s reply was/is reassuring with some sense of experience coming into play.