This is an ideal plan is for those who have a goal of climbing a large mountain such as Denali or going on a Himalayan expedition for an extended period of time. This 24 week plan progresses gradually. Each of the three 8 week periods serves a different purpose and is not meant to be a stand alone program. Stick with this plan and you will see great results.
Familiarize yourself with the training concepts and principles described in Training for the New Alpinism. Especially the notions of Continuity, Gradualness and Modulation. Rest when you are tired. If you miss a workout do not try to make it up. Just move on. If you miss more than 2 in a week then repeat that week.
Do not increase the intensity and hope to gain more benefits. There is no short cut to when it comes to aerobic adaptation.
This plan has proven very successful for a number of climbers all over the world who successfully used it to prepare for difficult climbing objectives including ascents of Everest without supplemental oxygen.