Which is supposed to be the main bb eb key? the side one or the rh1 ring

This feels really funny to ask as an intermediate player, but I'm blind so hardly ever see people played. What little private lessons I had, the teachers never mentioned anything. So I've always used that side key to play every eb and bb, but now that I think about it, is that key suppose to be the trill key and rh1 is the default? Or is the lh1 rh1 fingering hardly ever used?