That seems fine for 40-50. At 20 it is about the same because you only have 3 per city and the level 10 ones stop giving decent rewards after you exceed their level range. You also have very little else you can do in this range because of the lack of low level parties. This is where the problem comes in. Solo grinding is terrible xp, behests don't have anyone else doing them at this range either so you can only do them if you can solo them, etc. Add to that the 3 leves per city in this range and all 8 would not even give a level plus is more than the anima you would have. That part will at least be better after the transportation patch.

I would expect that 1-2 levels per day or 1.5 days would be more appropriate, but that also would include the ability to actually party which is missing at these levels. You end up feeling stuck because of the lack of opportunity to advance and that makes the game discouraging to play.