The sections of the bridge fro the viewer to next to Spock's station were typically pulled out for camera access, and often the crew would just cheat the "command module" this way and that to get shots they needed without having to push the bridge back together.
Cool. So, this explains another puzzle I noticed years ago in The Doomsday Machine. In the teaser, when Kirk is walking around from the viewer to Spock's station, one station is missing.