argumate:

season one of Stranger Things was trying to create a new and original show and season two of Stranger Things was trying to continue that while staying true to the basic premise but by season three it’s like buckle up kids you know exactly where this is going yep we’re doing it again and I mean that’s okay if you ride the rollercoaster three times you can’t expect it to take a different route each time.

When did seasonal arcs become a thing, it must have been after the 80s started doing continuity but before Buffy could be self-aware about “Big Bads”. I guess sweeps-timed (television viewership, and this valuability of advertising time, was sampled in particular, known periods, and shows made particular effort to capture audiences) multi-part episodes were an intermediate form.