Complex sentence: Through the first three seasons up to 30 episodes were broadcast, unlike later American television series with fewer than 25 episodes each year which allows more breaks in filming, along with fewer promotional appearances for the actors.
Split into simpler sentences: Through the first three seasons, up to 30 episodes were broadcast. This contrasts with later American television series that shoot fewer than 25 episodes each season, allowing more breaks in filming and requiring fewer promotional appearances for the actors.