Great tests!
Would measuring the lux at a distance greater than 1m be better for focusing? With the luxmeter close to the reflector you could have a converging beam (fig. C) that at 1 meter reads higher lux than a parallel beam (fig A) but would perform worse at greater distances as it would start diverging past the convergence point. It probably doesn’t matter much with a small reflector but I think that’s why people like to test larger throwers at 10+ meters
