IASIP, after 10-12, the show went on for too long, and the actors clearly are getting too old and tired, but they are addicted to the money, and hollywood lifestyle. SPN, after season 8, most fans are wtf is even going after that, eventhough 11 had a good run because it something different. every season after 8 was fanfiction/slashfiction.

and allegedly the actors in isaip did 2 year per season stints, and it worked for a while, but since its such a long length of time between seasons, they aged so much after reaching into thier 40s, they had to use botox and plastic surgery to catch up with appearances, it was so cringey.