I have read and heard something similar, and my (limited, since I chose to get OUT) personal experience backs up the idea... if I had just been left alone to do my work, I could usually have completed my daily tasks in about 2-3 hours... and yet I was trapped "at" work, often for 8-11 hours daily, six days a week. And it was nuts...

we are fighting activity vs productivity

Precisely! And I found that even when I was not tired, I still was mostly doing "busy" work of no particular meaning... and the eternal "triple CYA" process: sending emails to people to let them know that the emails I am going to send them will be sent later."