Well it all kinds of depends on what you mean by working on an episode. There are usually several in production at the same time, usually in different phases of production. After they've settled on the script, they usually research the locations and this is done well in advance of actual filming. You also have more than one director working a show. Second unit's do things that are peripheral to the actual actors being involved. I've even heard it done on other series that when they are on location and they know they are going to be needing a scene in a future episode from that same location, they shoot it them while they're there. After that is sound dubbing and editing. I believe it all takes place over several weeks. The actors could be called back to do a loop over on a previously shot scene from a previous episode. RDA has mentioned that he being one of the producers, he sometimes works seven days a week. On Sunday he'll fly down to LA and work with the editors. Must be a hard life.
The Gekko people are Richard Dean Anderson and Michael Greenburg.
Cheers,
