Yeah, they kinda are. Son of Kal-El ended when Clark came back and they re-launched the entire Superman line. The only book that didn't get a numerical relaunch was Action Comics. it was a line-wide relaunch, hence Jon's series ending and re-launching with a new series like DC and Marvel do constantly with their books with every line-relaunch. The only line that tends to not get impacted by this business model is the Bat-brand, and even then only Nightwing, Catwoman and Harley tend to leave unscathed.
Last Read: Aquaman & The Flash: Voidsong
Monthly Pull List: Alan Scott: The Green Lantern, Birds of Prey, Daredevil, Geiger, Green Arrow, Justice Ducks, Justice Society of America, Negaduck, Nightwing, Phantom Road, Shazam!, Suicide Squad: Dream Team, Thundercats, Titans