FWIW, when I rebuilt my old Motobecane, I found the BB contained 7 balls in plastic retainers on each side. I replaced these with loose balls, 11 per side. I actually tried 12 balls in one of the cups (in my hand) to see if they would fit; they caused the shaft to bind. I expect the new shaft to last longer with more balls. Two prior crank axles had worn out since I got the bike.
I was unaware that there are cages that hold 11 balls, but working with loose balls was not difficult.