The proposal for determining SG based on a small sample is valid but in my view very susceptible to human error and ageing eyes. With my equipment and capability I could not hope for a SG with a 5 decimal point accuracy.
5 decimal places isn't needed. For the purpose of making mead, it's very simple: Estimate the required amount of honey, mix it up and take a measurement. If you need more, add more. A few points one way or the other doesn't mean squat in the end result. Your yeast will have more variability than the SG. Really, it's not rocket science.