You can define your very own seasons/time tables both in ASC and RR. Length of seaosn, circuits, cars, race lengths, pitting or not, all can be set by you. Or join a seaosn table when preferring online. For the latter dont ask me, i don't play online much. Competizione has a championship mode, too, but I never tasted it. But hey, Competizione is the official title for the Blancpain series, so... go figure.
I did complete season championships in Grand Prix 1 (
), and years ago i did two DTM seasons in Raceroom.