I am more careful about testing in company, as there is often blood and not everyone likes the sight of blood. But then, so many people are fascinated by what I am doing and some feel its sufficiently of interest they'd like to see what their BS is.
Ok, so I waste a test strip, but they share a little of what we go through and I'm educating them.
As for needles and lancets, I change them if possible everytime I use them. Always if I test someone elses blood!
Some view it as wasteful, I view it as following advice and guidance, if I get infections or sore through using needles too many times, I have only myself to blame. My doc prescribes me enough for every injection and every test strip I use. So I use them.