Do you have any sleights that you practice, but never actually use in a routine? I'm sure most magicians have at least one or two -- pending they practice sleights of course. One of my big ones is mucking.
I love mucks. The idea of one card in plain sight on the table being switched with another just by passing a hand over it, it just seems so magical. Yes, I know, it's a gambling thing. But that's not where my interest in it is at, nor where it started.
I remember very well my first introduction into the concept too. Unfortunately, it wasn't actually a muck. It was a video by Daniel Madison, either on YouTube or Instagram, and in the video he slapped his hand down on a face-up card and when lifting his hand, the card hand changed. I can't find that original video (the guy's got a lot, and that specific video wasn't about that), but a little while later he posted another video titled Camera Tricks - Slap Change Tutorial where he shows that it was actually, yup, a camera trick where he edits the video. Yay.
However, that has been my driving inspiration when it comes to mucking. Just waiving my hand over a card or better yet, just slapping my hand down on it to change it!
A few years ago, I discovered Jeremy Griffith on Instagram too (@lost_angelus) and in one of his videos (and he does this a lot, I've come to learn), he performed a card muck. And then did it again with two cards! "Holy hell," I thought, "that's exactly what I want to learn!". Thankfully, IG's super helpful comment-critics dropped the name "muck", which I didn't know at the time, and it led me down the rabbit hole.
I think I've been practicing mucking for maybe 2 years now, off-and-on. I thought I was getting pretty good at it at one point so I setup a camera to record and yikes. Flashing left and right, finger windows open, and just general wonkiness. It might be a good time to invest in a 3-way mirror!
Again though, I know that this has a gambling application to it but I don't really do any gambling routines. I have enough books and video material to solely do gambling routines, and I've learned plenty and enjoy them, they just don't come up in my very seldom performances. But hey, one way to think about it is that it's giving me more time to practice my mucks =P