Well, i can't say with a 100 percent certanty, but i do believe its for real. And yes, its very nice.

If i'm training an ST and i use GK-training in the first 5 "blocks" and then the skill drill (very easy intensity) in the last "block", he will gain massive in creativity, heading and dribbling. Much more than he would have gained if he only was trained with skill drill alone.