After the monk tree quest, I did the air elemental power monk quest, where you had to solo some exp (320k, since it was my first elemental power quest) in one hour and then kill the elemental lord.

Soloing the 320k exp took about 25 minutes and then killing the lord took 5 minutes.

You have gathered the experience required within the time limit.
You still had 34min and 54s left. The trouble is, your actions have attracted
the attention of an elemental lord. It will soon appear to wreak havoc on your
sorry self. You can't just leave it wandering around -- you need to subjugate
or defeat it. For this task having a party might help. If you die to the lord,
you will have to try again later.

...

You have a new solo kill option for top10!
Air mephit lord exclaims 'Bested! By a mere mortal! Shame on me!'
Air mephit lord buries its face in its palms.
Air mephit lord goes *plop* and vanishes, subjugated.
As the elemental being vanishes, you have completed the task. Congratulations! 
New bonus gained: Access to first elemental ki-power of your choice: air.
New bonus gained: Access to Unsu kata.

This was my second time with this particular quest. Previously, I did the quest a year ago, also as a human monktarma. At that time the exp collection took 10 minutes longer.