I get a lot of comments from guys in this phase, things along the lines of "you can really screw up with your training and still put significant muscle on" and "there seems to be a large margin for error in this phase...I didn't have time to train that much and I still gained a lot of muscle".
There's good reason for this: you don’t even need to weight train to experience some muscle gains. That's not just my opinion. A study done on 6 men showed 4 lbs of lean muscle mass gained, with only 2 lbs of fat, when they ate excess calories with no weight training (Am. J. Clin. Nutr. 49.4 (1989) : 608-611).
Another study published in (J. Nutr. 109.3 (1979) : 363-377) measured differences in net protein utilization in the diet between 15% and 30% over maintenance calories. These are similar to the caloric levels recommended for the Feast Phase in The Blueprint. They found the 30% group used more protein, therefore they were increasing protein synthesis and thefore muscle mass. Also, a large increase in Testosterone, Insulin and IGF-1 was observed solely as a result of this over-feeding. The point is, simply eating an excess of calories has an anabolic effect.
Throw in the fact we re-introduce protein into a starved system, add in adaptogens, sophisticated de-loading and do all of this in a deeply alkaline state and you can see how growth is a no-brainer.