I don't know how many characters were on the old system. Probably a couple of hundred.
I tend to play three or four different characters at a time, alternating between them. Sometimes I roleplay that they are connected to one another, and I make small mods to drop appropriate items into the world for them.
Some characters become very significant people, wellknown throughout Tamriel, and do a lot of quests, while others just get caught up in small personal stories. Some get dropped, as I lose interest in what they're doing, while others go on for months. One of my presently active characters has 166 hours; that may be my record, because while my characters never do "everything," Fortja comes the closest.