well i dont know azcs nor have i ever seen how good or shitty their op is but ill dive in blindly to make a possible point on what that looks like he is doing...
as he said and was a sampling of cuttings/clones in a TEST setting to see which nutrients work better on which strains...
advanced growers and breeders do this all of the time to get the most accurate tweaking of which nute product will work the best for which strain...
and since they are working with cuttings... this makes the "control" of the test that much more accurate due to the fact that the clones will all be from the same strain
now if he has like 5 or 6 different phenos and or 5-6 different strains of cannabis in the same bucket with them all sharing the same nutrient solution then that would make him pretty lazy shitty and dumb to do a test on which nutes work best with which strain...
because then he is just complicating and things and would be much easier and incredibly more accurate to just take only 2 cuts of each pheno of the same strain... this is because each pheno will react completely different to the % of npk ratios and if you have too many strains or phenos in the mix you wont be able to narrow down what nute did what
so in order to get an accurate sampling you would have to isolate down to the ppm and chemical composition of the nutrients to "dial" in on which works the best for each specific pheno and or strain more or less on an individual basis...