That's my bet; and so this 30-ish (I'd give it +/-5) year lag is the same reason that, when Back to the Future came out in the mid-80s, they traveled back in ti

That's my bet; and so this 30-ish (I'd give it +/-5) year lag is the same reason that, when Back to the Future came out in the mid-80s, they traveled back in time to the mid-50s; why Forrest Gump centered on the 60s during the 90s; why That 70s Show was popular during the early 00s; why the now already decade-old Stranger Things was set in the 80s; and how 90s nostalgia has become "a thing" semi-recently. Happy Days was big, and was set in the 50s while being from the mid-70s... but, I'd argue it could have been the early 50s, the show was on for over a decade, and AFAIK it wasn't an immediate hit (though it also didn't have the Fonz at first); also, FWIW, there was also a big nostalgia boom in the 70s that was focussed on the 40s (see the video linked below), so I would just lean on +/-5 years as why we see little discrepancies. https://youtu.be/l0ZXItfw5r4 https://youtu.be/l0ZXItfw5r4 "[A behavioral scientist we asked about this] determined that we are not really all that happy about the present, we are terribly uncertain about the future, and when we talk about the old days we always refer to them -- I suppose because of our collective memory -- as the good ol' days; and, I guess, really, when you go back, you really can select the better parts of the good ol' days... like the music." -- a radio executive in the 70s