Interesting to compare!
My bees almost never go on the top shiny silver metal outer cover at all, and I never see any bees on the top cover on their backs.
I have an open screen BB and a slatted rack inside, and every 10th bee or so that comes rushing out of the hive winds up doing a little somersault as she comes out, all excited, and winds up on her back on the 'landing pad' for a moment, then rights herself and flies right off like it was nothing. They never seem to tumble when going back in.
My bees are part Russian, part mutt as far as I was told.