Yeah, that's correct. Your XP per kill will increase incrementally as you level up, it will then peak and begin slowly falling again. You should be netting a level per clear of SM Cath (roughly) And that will continue as you level higher, to almost 2 levels per clear. At 40, move on to BRD, 50 to Scholomance or Strath up to 60. (I did Scholo for the Runes for my Palis Mount, and for all of those nice caster drops to replace the level 1 gear my Mages were still wearing).