Doug, I would view keeping the agreement with the employer as getting the required work done on time rather than being occupied every minute and slack periods can occur. I have known bosses who have tried to find extra work or even invent work rather than see employee's idle but I believe this policy tends to be counter-productive in the longer term.

Also, how many of us are capable of working on something for say 2 hrs solid? I know I'm not. Taking an unnoficial 5 minute break can again be more productive than trying to slog right through. Ever done a cryptic crossword, reached the brick wall, put it down, had a coffee, come back and got going again?...

Jon