What is the "time control" that the men experience in the institution? What caused the chief to notice that nothing has been worked on all day?

Bromden thinks that Nurse Ratched can control time. This is because she heavily controls everything in the institution. She micromanages the lives of these men to the extent that she controls their time and reality. It is as if, to the men, she can speed up and slow down time. The only time Bromden feels free of time control is when he is in the fog.