Interesting all these jobs you do actual deliverable work versus a management postion that it becomes much tougher tell what they do. My observation is management forces you to work long hours to keep up appearances, since telling a good manager from a bad one is not a straightforward thing.
Well, unless you work for them. :-) I remember the IT mgr for a company in Dallas that bought our company. I could tell that in the past his technical skills were probably pretty good, how he got to manager in first place. But this company was so ate up politically that this guy came to work every day at 7am and went home about 8-9pm at night. From a getting work done perspective it made no sense, he was just "showing how much he cared". Didn't do him any good, about a year after they bought us they got bought and ceased to exist.
Another anecdote on this hypothesis. My current company implemented Lean, which part of the system was having weekly meetings between supervisors and their reports, updating to a cockpit chart. I jokingly asked why nobody wanted to meet with me weekly to get project status updates. Our Plant Mgr replied "we don't need to, we see and use the work that you do". That's a good place to be. Well, unless you actually like meetings. :-)