I'm assuming you are referring to the 'Penetration Testing with BackTrack' course hosted by Offensive Security. The videos provided by them total about 8 hours in length, and you also get a ~350 page PDF lab guide. The average time to complete the basic exercises is 80 hours - but that will obviously depend on your technical background.
80+6 hours spread over 720 hours (30 day window) is perfectly reasonable to achieve.



