Marvel's Agents of S.H.I.E.L.D. returns March 4, 2014.
There are two primary reasons Agents of S.H.I.E.L.D., along with other full season drama shows, have multiple breaks in the season that are usually filled with either repeats of earlier episodes or special event programming.
- Filming Schedule
Each episode takes 8 work days to film and after the episode is filmed it has to be produced including cutting/editing, adding sound, ADR (Additional Dialogue recording), adding music and in S.H.I.E.L.D.'s case adding visual effects which all take time. In total it takes approximately five weeks to produce one episode of Agents of S.H.I.E.L.D. If a new episode aired every week there would not be enough time to film and produce each episode in time to air.
- Broadcast Schedule
A full season order for a drama series on ABC is 22 episodes, occasionally additional episodes will be added bringing it up to a maximum of 24 episodes. The season begins in September and ends in May, around 35 weeks. Simple math makes it obvious that to draw the season out to fill the season's schedule there will need to be breaks.
From time to time these scheduled breaks will be planned to coincide with special events (like the Olympics) that make a certain date a logical one to skip but these are not generally the primary reason a week is skipped.
So ignore any rumors or speculation you may hear about why ABC is not airing a new episode on any given week, there is no concern on the part of ABC or Marvel, there is no secret reason or hidden conspiracy or evil intent, it is simply a practical and perfectly routine issue that affects all network dramas.