Larry, I very much appreciate the information you have shared, the details/opinions you give....and your honesty.
I have learned more from this thread than expected. It has cause me to question my methods...methods that seemed to have worked for the 50+ years I have been putting holes in paper. I am reminded of the phrase, "You don't know what you don't know".
I have a new Howa .223 bolt gun I am loading for, and a new hunting bullet for one of the .308's I am wringing out. I have already made incremental loads for the .223 using 5 rounds per charge. Your opinion regarding at least 10 rounds to determine ES and SD makes sense. Even with my method of 5 shot groups I fire 5 groups to "prove" a load as there is too much variation to depend on one "wallet" group to tell the story.
With the requirements I have, varmints to 300 yards and deer to 400 yards, it may not matter much, but I have decided to at least try a more rigorous method as you have suggested. "Wasting" components and trigger time is never a 'waste' anyway...LOL.
I will still award the chronograph (maybe lightly used) or its equivalent value if I decide to keep it.
Again, thank you everyone for contributing.