I am happy with my recent 10" strops, but also with the 16" 0.1u/200k strop they enabled. And I refreshed my 12" strops and use those. Variety!I have been experimenting with 6" long pieces.
Also, I had not heard about the straight edge / feeler gauge technique. I doubt I'll invest, but it would be fun to test balsa flatness over time and atmospheric conditions that way. It doesn't take much to get me to invest in test/measurement gear. I have at least three feeler gauge sets already, left over from a time when I would touch an engine myself.
If I test a machinist level with three feeler gauges against my granite surface plate that is five standards in play for the one test that relies on my sensitive touch and judgement. I'm glad I never knew about all this stuff when I was adjusting my motorcycles' valves and points back in the day!
If I get a high spec straight edge, am I seeking truth or just indulging my tendency to overpay for backing up my 2¢ opinions?