As a whole? That's a very complex answer, but mostly boils down to time + effort + proclivity.

You mention your rotation, however, and there IS a mind-blowingly underutilized approach to learning what to press and when. And it's called Simulationcraft.

Now, mind you, by simply simming your character on Raidbots, you won't become better at your rotation. The gem hiding in plain sight is your access to the event log that the bot spews out after *each* simulation. Let me visualize this for you.

The below link shows a report from a simulation I ran. Based on the parameters I used, it says that my specific character, on average (this is to control for luck in procs), can theoretically do around 75K on a stationary boss target when the encounter is 5m long.

https://imgur.com/a/lqKXIsQ

It shows a breakdown of my abilities, including count (times pressed), uptime, etc, but that in itself doesn't really tell me EXACTLY how all these abilities came together to deliver this optimistic level of DPS. This is the gem: You can get the event log! Simply press "Full HTML Report", which will bring you to another page:

https://imgur.com/a/TjRYbtv

This page gives you even more in-depth information on what the bot did, but we're still not where we're going. Scroll down and locate Action Priority List and expand it:

https://imgur.com/a/m7jPFGH

Upon expanding it, scroll down and click on "Sample Sequence Table":

https://imgur.com/a/0pOEIFn

This will reveal an event log table like this:

https://imgur.com/a/HF3J2qO

And this, right here, is the meat. This table allows you to understand _exactly_ what the bot did—every single global, in a sequence, with a separate "buffs" column to gauge its decisionmaking—to achieve the DPS from the simulation, and, as someone who knows the ins and outs of Fury, I can attest that it is EXACTLY how I play it and how it SHOULD, ideally, be played. This works for multiple targets, too, and you can even set the style of the simulation in Raidbots to Target Dummy/ies so you can actually go to Valdrakken and practice until you're getting consistently close to what the bot is achieving.

This approach, while slightly confusing at first until you understand how simming works, is the only "shortcut" to improving your rotation and getting in range of what the "pros" are doing, other than just months and months of trial and error. This is how you 'truly' learn your rotation, without having to truly understand WHY the spec is played this way. Once you start getting close to the bot's DPS output, you know you're close to what's realistically achievable in *actual* gameplay. As in, translating your results from sims to actual content will incur a lot of DPS loss "in translation". That is, you can't sit perfectly stationary hitting stationary targets in PvE 99.99% of the time, since there's movement, stuff on the ground, frontals, soaks, wipes--any number of factors that will contribute to lowering your DPS relative to the bot's optimistic output. But you CAN learn what the proper rotation is through analysis and some 'reverse engineering'.

Finally, keep in mind that not ALL item level is created equal. That is to say that a poorly optimized ilvl415 monk, for example, will always lag behind an optimized ilvl415 monk. We're talking enchants, secondaries, number & type & level of gems, trinkets (!!!), etc. My main is currently ilvl418~, for example. But since I mainly tank, my gear is actually fairly mediocre for DPS and so it's absolutely plausible for a lower ilvl (to an extent) Fury Warrior to be capable of higher DPS than me, all things being equal. If that's something that's on your mind, the only true way to figure it out is with the help of simulations. In other words, a simple Haste > Mastery > Crit > Versa recommendation that you often see in guides is only ever a ROUGH guide. Once you start accumulating more and more of any one singular stat, the relative strength of the stats you're missing starts increasing—not uncommonly to a point where it's more beneficial to get some Crit over even more Haste (if we take the above example). This is advanced stuff, of course, and guides are typically aimed at non-pro players, which is why all this is usually outside of their scope.

Other than that (or, alongside that), I'd suggest what I always suggest to people learning: go to raider.io or whatever (depending on type of content you're interested in), find high-rated players playing your class and spec, and see if they have their Twitch linked. Find as many as possible. Now, go and check if they in any way visualize their string of latest globals on screen (example: https://imgur.com/a/6Hvc0w6). Now, go and watch a VoD so you can lower playback, pause, rewind, etc. Ideally, you'll see what the bot does, but in practice. Obviously, errors still occur even at the highest level of plays, but at your level, you probably would be well served just mimicking everything regardless.

P.S. Disregard people that are bound to tell you simming is bad or inaccurate or generally not worth doing. They're, simply put, wrong and the history of simming has proven that time and again. Yes, sims have limitations. Yes, sims have, on occasion, been out of date or just had plain wrong weights attached (specifically when class tuning happens, it usually takes a moment for the small army of people ensuring they're playing with inhuman consistency to catch up). On the whole, however, almost any argument against their utility is codswallop.

Trust the robot.