On a lot of things, and not just from CBS and Paramount-- Fox has done it too, w/things like The Fall Guy and St. Elsewhere, among others.
We've had stalled movie series, as well. For example, the Michael Shayne private eye series starring Lloyd Nolan consists of six Fox films. Fox released four of them in a nice set, one as a stand-alone DVD, and one as a MOD Fox Cinema Archives release. The sixth, Time to Kill, has never seen the light of day, not even on the Fox Movie Channel. That is incredible frustrating to collectors who want complete sets. Five more were made by PRC with Hugh Beaumont playing Shayne, and those are available in a box set.