Absurd precision

In the battlefield, facing the enemy army, the general ask his aide-de-camp:
- How many soldiers do you think there are in the enemy ranks?
The aide looks for a little while and respond:
- One thousand and three, my general.
- Amazing! How can you tell this precise number so quickly?
- Very easy, my general! There are three in the first line, and about one thousand behind.
I like this joke a lot. And I think it teaches a lot, in a very simple and humorous manner. Performance is about measuring, calculating and quantifying. The values must be presented with the right precision, but no more. Otherwise, you are inventing.

I doubt you could report  67.953% usage average, but 68%.  Or, perhaps even better, between 65% and 70%. You cannot arbitrarily add (absurd) precision. I'm not trying to teach error theory here. Only warning you to be careful when giving quantities.