LED Positioning Question...

Emitters being off-center are by mistakes. Even with highly precise machines aligning the emitters to the assembly, there will be some deviations.

I work in manufacturing (not of electronics) and can vouch for machines assembling things with variation in placement. It's usually not going to affect you in light output or beam quality, but some people get twisted knickers over it. The reflector probably focuses on a tiny fraction of the LED.

Point the light at a distant light source while it's off. That light will focus on a tiny point on the LED. This is a good approximation of exactly what percentage of the LED actually shines into the spot of the output. Most lights project some of the output (that which strikes the reflector) of some of the LED (that which is lit in this demo) into the spot. The rest of the photons are spill (never hit the reflector) or corona (non-focused parts of the LED output) that surround the hot spot.

I use this test to see which mag lites and other store bought lights are the best-centered for gifts.

hmm,
LED positioning variances can be compensated by texturing the reflector, so unless the reflector is smooth a defect with an off centered LED should only possess cosmetic value. Most off the shelf consumer grade lights with textured reflector an off centered LED is often not noticeable in use unless you're constantly looking into the business end.