Syfy channel aired another Twilight Zone marathon, where they aired episodes of the classic TV series all day. They've done this before, and they weren't the first to do so (at least in my experience); I recall local station KTLA running TZ marathons on Thanksgiving 30 years ago. Suffice it to say, I've sat through many a holiday in front of the TV with Rod Serling's collection of fantastical morality plays airing in succession, and have seen the majority of the episodes numerous times.
Obviously that's the reason a station or network would choose to schedule an annual marathon: The show lends itself well to repeat viewings, making for a good background for holiday gatherings (particularly for those who aren't inclined to watch sports, or when one's team is getting blown out in a bowl game) and moments of "oh yeah, this is a good one" and "you've never seen this one?" to spur those times when you've run out of topics of conversation with your relatives.
(It may be also that it's relatively cheap to get the rights to air TZ episodes.)
Produced in the late '50s and early '60s, the show did not have impressive special effects (by contemporary standards) or necessarily phenomenal acting, but the writing was generally strong. And by that I mean the stories and the twists; the dialogue was about standard for the time. There's a certain extent to which one must give oneself over to the convention of the form to really appreciate it.
Part of the effectiveness of the show also flowed from the way it was filmed. I don't mean the cinematography, per se, but the fact it was shot on film. The muted tones of film work well with the black and white chromatic palate. It also helped make the ominous parts of the stories seem a bit more ominous. This fact is reinforced by seeing one of the episodes from the second season when they briefly changed over to shooting with videotape.
During the recent marathon I saw the episode "Twenty-Two" which is one of those videotaped shows. The higher contrast of the appearance as opposed to the film makes the tale of a fatigued actress who has visions of a morgue (in Room 22 of the hospital) seem less about anguish and more a paltry early'60s soap opera (the likes of which were also shot that way).
In short, those episodes always strike me as not quite right, as the second string of the collection, regardless of the quality of the stories.
That's probably why those don't air during the marathons: the presentation matters to the overall experience, and with those the experience just is not the same.
Also, on the TZ topic: Every time I see the marathon I am reminded that I wonder what show presently airing (or having aired recently) could possibly be the source of a marathon 50 years from now, something where it has enough episodes to show over and over; where it's not serialized so they can be shown in any order; where it doesn't require full attention to watch (that background quality).
The only show that comes to mind to fit that bill (for me): The Simpsons.
Obviously that show is different in tone than TZ but given it being the longest-running primetime comedy series (now it its 22nd season) it will have way more episodes so the marathons can go on for full weekends and have plenty left to not repeat at the next holiday weekend. (And the only reason it won't require attention is because the episodes will have remained airing on Fox stations for the first 30 or so of those 50 years; after 20 years away people may be ready for marathon sessions.)
Although there are quite noticeable changes in the quality of the animation from the early seasons to the later ones it's not so drastic that it adversely affects one's experience of watching (although the episodes from the really later seasons won't air as much because, well, those aren't generally as good, so there will be some analog with the TZ videotape-shot ones).
I'm sure the animation will seem quaint relative to what will be the norm in 2061 in the same way the effects of TZ seem now, and there will be plenty of cultural references that only those who have studied the early 21st century will get (not unlike how kids of today may not grasp all the Cold War overtones of many TZ stories), but I do envision a world of tomorrow where Matt Groening's characters will still be entertaining enough to immerse ourselves once or twice a year.
And The Simpsons have paid homage to/parodied TZ in their annual Halloween "Treehouse of Horror" episodes, so when one of those airs it will bring everything back around full circle.
Around that time perhaps someone will wonder what series of 2061 will be the go-to marathon show in 2111.
So what do you think could be marathon-worthy five decades from now?