My experience exactly, will continue with this method /\My conclusion is OBT is like a stopped clock. It’s right twice a day. None of my best shooting nodes correspond to the calculated ideal OBT times. Not even within 20%. This is across multiple guns, calibers, powders, bullets, etc.
I have better luck shooting 0.3-0.5 gr increments and finding the accuracy nodes that way. Then refine with 0.2 gr and refine and determine repeatability.
Doesn't matter how you get there.....long as you get thereTo each their own, more than one way to skin a cat