The other pro for MAF is the aerobic capacity you build with it will allow you to train with more intensity/volume on your other training days. MAF is a simple progressive overload that requires little recovery. It's really the main benefit of it. If your dad is a 20 minute mile hiker at his MAF hr today he will be a 15 minute mile hiker at his MAF hr by November. I wish I would've known of this training style in my twenties because I went through several of the programs listed my mckolorado from the MTI company and they created a lot of imbalance and have poor coaching in technique and doesn't really have a great grasp on how to build programs. Don't get me wrong, I was in excellent shape but the long term cost to my joints was pretty high. My physical therapist was shocked at the programming from MTI and said he could see why my back and hips are 20 years older than my age group. I follow the stamina and apex programming from SOFLETE which has been great for me in conjunction with physical therapy. I drank the Kool Aid from MTI for about 10 years. Im no novice in the training realm and have been a Wildland Firefighter for almost 20 years. Anyways I'll get off my soapbox