I'm level 25 and still got enough quests to get me right to 30.
Level 1-30 - In Normal pure questing, no grind. Did not skip a single quest. Was Level 30 when I fought Syndonai.
Level 30-31 - Questing my way to Shulgoth.
Level 31-40 - Raping Shulgoth over 700 times.
Level 40-49 - Mainly doing experience runs from Temple Station to Charing Cross Station.
Level 49-50 - Monument Tunnels and Monument Crawlway.
~Kinky.