also, speaking of the British, and sitcoms, and recommended-optional poli sci class syllabus assignments, Yes, Minister and Yes, Prime Minister advance from season to season as the party's fortunes change, Hacker's department changes in relevance and he eventually becomes PM (hence the series name change) as well as his understanding of how to manage Sir Humphrey and the bureaucracy he represents, along with Bernard and Humphrey's personal relationships with Hacker evolve
and another sitcom that I've made a thread about here, Newsradio perhaps ironically, much like AD, as its fortunes waxed and waned, produced seasonal-arcs and multi-seasonal arcs, most notably in who owns the station and how it reflects on Dave/Jimmy's situation and then of course when Phil Hartman died
Larry Sanders Show another sitcom, albeit one on HBO, that was doing the ongoing plot format before the "revolution" of TV that led to it appearing everywhere including on broadcast TV where it was once considered impossible to pull off
One argument is that NBC was unintentionally producing this type of sitcom as its number one hit for longer than anybody at the time realized, as Cheers, Seinfeld, Wings, Frasier and Friends all generally did not "reset" affairs as often as other shows, even if it maintained the main outline of the series (actors changes helped Cheers/Wings do this long before it became in fashion or intentional) and a lot of it was tweaking in-show relationship setups. (Seinfeld most notably introduced gobs of outside the foursome characters to avoid this.)