Season 4 was able to air three complete yet connected arcs within the span of a single season without any frustrating gaps.
Breaking Season 4 up into arcs was probably quite helpful for those of us who have been frustrated by Agents of S.H.I.E.L.D.’s hiatuses each year.
In Seasons 2 and 3 in particular, there was a span of around three months between the midseason finale and the midseason premiere, and a lot of momentum and cohesiveness can be lost when there’s such a huge break in the action.
Each season since the first has been split up by surprisingly long break.