Osmolality Testing of Liquids

It is more normal to take a measurement 3 times before averaging. I'm sure someone well versed in statistics could tell you why. Just intuitively, one measurement could be a fluke. Two flukes in succession is very unlikely, but if one is a fluke, then the average of the two is obviously biased. Therefore three measurements is the bare minimum to make before averaging. It's certainly what they use in the measurement of elemental composition in analytical chemistry.

Other more tedious methods would be to take 10 measurements, chuck out the highest and lowest, then average the rest.

For any scientific measurement to have a sound basis statistically, there should a minimum of three measurements (simply because some statistical parameters become essentially meaningless when the data set is so limited). Significance testing requires four results for a reliable Student's t test of confidence limits. Anything more than about 20 tests there is little to be gained in understanding the statistical distribution of data.