To micromanage, or not to micromanage? That is the question.

Love this discussion over at drug monkey.

And ok, I realize the question isn't exactly about micromanaging. It's about how to run a lab effectively. Should the PI know the nitty-gritty details of the science and techniques? Should the PI actually be in the trenches doing experiments? Or is the PI mainly a manager and fund raiser?

I wonder how, historically, professorships have developed into their current state? I've read some historical accounts of science. One I recall is an account of Millikan's oil-drop experiment. From the story, it sounded like Millikan at most had 1-2 trainees at any given time. In fact, Millikan is the sole author on the most famous of the oil-drop papers. (Although from what I read, this sole-authorship may have been somewhat shady.) Anyway, I wonder how the modern lab came to be, with several trainees per professor, and professors with more responsibilities than seem humanly possible to really handle well.