On german server I get almost every time I return from a dungeon 3 souls.
This changes a bit, but from what I can recall, this is the amount of souls I usually obtain.
But I am one of the luckier ones since there are quite a few players
who complain about not getting souls for weeks when they even go two times a day.
I don't know what's going wrong with the soul rate of those players, though.
Seems weird to me that there are some who won't get any souls when dungeoning so often.
Especially the high level players.