The only time I've really seen anything close to what you would expect to see from the tagline 'node testing' or 'ladder testing', is way out there where the small differences in velocity show something. Not a range I have easy access to at the moment... Also I think you have to be shooting in really calm stable conditions, off a solid rest and be on your game as anything else that introduces a variable that could conceal your results.
With the 300m range I have access to now, I've seen a couple of people try this and at the shorter distance while the results weren't as uniform as those above (which for a hunting group is pretty good) it still wasn't enough of a difference to show anything really useful.
I guess another option is you've managed to find one big node for that pill, powder and seating length combo...
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