Can you get get myth/hero crests from ?? Nullaeus every week, or only once?

Title, I didn´t try yet. I got the mount on day 1 on prot war and it was painful but manageable. Then yesterday I did it on resto shammy (free) and arcane mage (not too bad). So is the description correct and you can get rewards from it weekly per character? That would actually be nice, 30 myth crests is nothing to sneeze upon.