Ah that makes sense. I was thinking it from the wrong way -- i.e. the way Calvin&#x27;s dad explains how they discover the weight limit for bridges -- no need to test from small to minimum-amount-needed when there&#x27;s a certain, reasonable volume of blood that pretty much works all the time (and I&#x27;m assuming that&#x27;s been tested to some degree). Though I&#x27;m still surprised blood-drop-variance wasn&#x27;t just something studied frequently out of scientific curiosity and because it seems relatively easy.