I was leveling my CNJ not too long ago and I was getting a level about every 5-6 leves, starting at level 27. Most of the time I complete the leve within 6-7 minutes, never going over 10. The time consuming part is going back to town and getting more leves, but if you set a secondary home point at an inn, and your main at the camp you're leveling at, traveling is trivial.

If you don't have anyone to PL you (or don't want to do that) just set yourself up as looking for a party in the new search tool. Parties are the fastest method of leveling. You can do leves while you LFG. Even if you only do leves, if you're playing 2-3 hours a night, I'd think you could get something to 50 within a couple weeks.