You know what an overuse injury is — when you do too much of something that normally wouldn’t cause a problem. It comes on slowly and then one day you wake up and you can’t do that thing any more.

Or, to use another example, what happens when you keep wearing the same clothes or using the same set of sheets or towels over and over. They wear out really fast or get all pill-y and look bad and don’t feel so good either. As much as you might have loved them at first, now you just want to toss them.

Many writers of TV series and movie franchises ought to ponder these similes. I’m thinking in particular of the Doctor Who series. Used to be that a lot of different writers wrote different episodes (including the brilliant Douglas Adams, author of Hitchhiker’s Guide to the Galaxy.) When the series was “rebooted” in 2005, the head writer was Russell T. Davies, but many of the best episodes were written by Steven Moffat, including the two-part “The Empty Child/The Doctor Dances,” and “The Girl in the Fireplace.” When Moffat wrote the episode “Blink,” he gave us the scariest villains I’ve ever seen: The Weeping Angels. I was terrified of all statues for a long time after seeing that episode (and do you realize how many statues there are all around us?).

Of course the Doctor defeated them, but it was a near thing. But then Davies left the show and Moffat was put in charge. He immediately brought the Angels back for a two-parter. Again, the Doctor defeated them. Then they came back in another episode, and guess what, the Doctor defeated them. Moffat amped the odds up each time: there are four in the original episode, many in the two-parter, and in the most recent one, even the Statue of Liberty is a Weeping Angel.

And . . . yawn. I’m no longer scared. I feel the same way about the Daleks and the Cybermen. I also feel the same way about the alien from the “Alien” movies and all of the many, many derivative monsters that have jaws within jaws AND despite being reptilian with hard scales are also slimy and drool like a Newfoundland.

They’re trying to keep us scared by making zombies faster than humans instead of staggering slowly (but relentlessly) along. Peter Jackson in the second Lord of the Rings movie thought that giant wolves weren’t scary enough, so he gave us giant hyena-like creatures ridden by Orcs . . . sorry Pete, not scary, just wrong, as was your pink Orc in the last movie and the supersized Goblin King and Azog the Orc in the new Hobbit movies.

I’m as much a fan of “disaster porn” movies as anyone, but I laughed throughout 2012 which managed to combine them all: California falling into the sea because of a 10.0 earthquake, the Yellowstone supervolcano erupting, massive tsunamis inundating the earth . . . by the time the waves were lapping at the North Face of Everest I was on the floor with the giggles.

The folks at Syfy Channel (whom I am usually damning for their lack of foresight when they cancel perfectly good series like Eureka or Warehouse 13) have, to their credit, seen the ridiculousness in this trend to supersize old monsters and are churning out made-for-TV movies that are deliberately over-the-top, like Sharknado, in which killer tornadoes not only hit the California coast but scoop up schools of sharks and fling them into the streets where they do what sharks do despite being, you know, fish out of water. It’s a comedy, not a horror movie, and you’re meant to laugh.

In addition to revisiting old enemies and making them more/bigger, Moffat’s also been amping up the stakes in many of the episodes. Used to be the Doctor saved Earth at least once a season. But now saving the Earth is nothing. Now he saves the ENTIRE UNIVERSE over and over. Am I worried that he won’t manage it next time? Uh, not so much.

My favorite episodes are never the ones where the Doctor defeats the Daleks and saves the Earth/Universe or manages to reboot Time once again. My favorites are the small-scale ones. The Doctor hardly even shows up in “Blink”; we just see him in a video telling the ordinary heroine and hero what to do — except he’s actually reading a script that they sent to him through time, which they do not know when they’re watching the video (how cool is that?). I love “The Girl in the Fireplace” because it’s basically the Doctor saving one person from a terrible fate. She’s a wonderful person and we fall in love with her just as the Doctor does. When he saves the Earth or the Universe, it’s hard to care. We just don’t and can’t love abstract concepts like we do individual people.

I get that coming up with new things to be afraid of is a lot harder than revisiting old favorites. But have these writers never heard the axiom “less is more”? Or cottoned on to the idea that the scariest thing is the thing you don’t see? That’s mostly in your mind? That’s why the Weeping Angels were so scary that first time. And the first Alien – because we never saw the monster until the very end. I remember being terrified during Time after Time, a movie about Jack the Ripper and H.G. Wells. You never actually saw Jack kill anyone, but you saw his face when he was moving in to do just that – and then the screen would go black and you’d hear a scream that was quickly choked off. Terrifying.

I’ve been a Doctor Who fan since the Fourth Doctor. But I’m feeling like I’ve got a bit of an overuse injury since Moffat took over as head writer. In fact, I’ve hardly seen any of the last season at all.