Okay, you beam down your senior officers *in their areas*. The Captain
goes down. Now your First Officer, usually a commander, takes the helm. The
commander goes down, now the lieutenant-commander takes the helm. The
lieutenant commander goes down, now the major or a lieutenant goes down (I
know I'm muddying this a bit, just tracking the theory here). Divisions in
the military are specific; you don't jump from a command type officer to a
physician if one person leaves the bridge; it just Doesn't Happen.

In ST, it seems there is rarely any real chain of command; there are the
Top Guys, a few in-between button-pushers, and ensigns. There should by all
rights be LOTS of command officers of mid-level rank to fill that job. It's
got nothing to do with reality.

jms