So, here's the thing about the meta. While it's fallen into a pretty stable routine for the past few years, early on it was pretty different. In fact, ADCs used to have the solo mid lane before everything became very set in stone and Riot started responding to the growing meta focus by gearing champions more towards working within certain bounded design specifications.
Right now, the important thing to remember is that trying to switch things up can give you superior numbers at the cost of weakening another lane and making the duo lane grow more slowly. For instance if you take a support top to help a Wukong get some early kills, Wukong is also getting less xp from minions due to Thresh being nearby, and is probably pushing up his lane as well so he's more susceptible to ganks. Meanwhile poor Varus down in bottom lane has the enemy Vayne and Leona breathing down his neck, and he's pushed back to his own turret and is losing farm to the minions being eaten by turret shots.
Also remember that Riot brought in a wave of changes to the ways that turrets have armor and damage resistance through the early game in response to a wave of people who would take a very strong solo laner bottom who can hold his own against two people while pushing the enemy solo top laner out of lane entirely and taking an early turret for an advantage within the first five or six minutes of a match. Not to say that Riot isn't against strategies like this, but they've made the potential to get easy reward much less easy to make a choice between when faced with an increased struggle to do so while your own weakened lane could be struggling for no reason at all if it doesn't pay off.
Duo jungle CAN work, but it's reliant on a lot of factors. You'd want a very aggressive jungler as one of the two, to roam around the enemy jungle making their life hell while the more passive jungler farms up safely. The aggressor could possibly keep constant pressure on lanes, taking one or two camps between ganks, while letting the passive one have the rest. Tax the laners a bit more to keep up in gold and xp from minions, and possibly get a bunch of early kills or assists, and push waves up to weaken turrets through the early game while the passive jungler is starting to really rev his engine. However, I wouldn't suggest it. The jungle is already hard enough to get through as it is, and running two junglers limits the amount of gold and xp that's really available compared to a solo jungler, and they need every scrap they can get right now. I suppose you could try something more along the lines of two tanks buddying up to go through their own jungle pretty quickly, splitting gold and xp, and then working together to invade the enemy and overwhelm them with numbers. I can see a Volibear/Rammus combo working pretty well for something like this.
The sad thing to remember about all of this is that while experimentation is fine, after a certain point you have to accept that the meta is pretty firmly rooted in what it currently is, and probably won't be changing much moving forwards. It isn't the worst thing in the world to have set routines in a game. Consider how frequently RPGs tend to rely on one physical damage dealer, one magical damage dealer, one tanky guy, and one healer for instance. Ever so often you'll see some variation, but that set up is the most tried and true because it's straightforwards and it works. You'll see pros pulling some really interesting stuff, but it's preplanned, not off the cuff. They aren't suddenly deciding to do this in champ select out of the blue, they've learned when and where to call in a strategy like a lane swap, or a duo jungle, and when you see them streaming these things they're experimenting, usually doing well because they know the game WAY better than us poor plebians.
I hope I shed some light on things for you.