It's not really 7 days per week, the basic template is:
2 days mainly upper body pushing + some legs
2 days mainly legs + some upper body pushing
1 day upper body pulling
The other 2 days are just active rest.
But that's still a lot of work, basically four full body days per week, plus a back day! There aren't many other programmes out there that recommended that sort of frequency and volume. Although I like a lot of aspects of HP Mass, I'd be cautious about the recommended frequency and take into account that this site is funded by a supplement company that sells a comprehensive range of pre and post workout supplements. The more often people work out, the more they'll use of their product.