Ceiling White Paint REALLY Works!

I have a number of headlight mounting buckets that I'm about to de-rust & re-finish. I noticed a long time ago that some sealed beam lamps had the silvering selectively missing, ........the '92 Chebby G10/Sportvan I just picked up has them painted black, some are galvavized, some appear to be painted gray/body color overspray. Is the desired bucket finish affected by the type of sealed beam, i.e. low/high-low/high, or does it not matter?
I know I cleaned up some buckets on a rectangular 4-lamp system, & the bottom of the one pair only had a strip of silvering up the middle, the lamps were brighter new of course.......but seemed better than before w/new lamps. Is the missing silvering intentional to reduce up-scatter light, or just cheapin' out, (I believe they were Wagner Halogens~'90)?
So I just looked at the new H4666 Extravisions I have, reflective silvering missing on the bottom, for the smaller rect. 2-lamp system.....My 1st-gen Dak & '88 ShelbyZ.....so what say You @slantsixdan ??? Should the headlamp bucket be white, silver, gray, black...???