It can be learned in a day, and perfected in a single season.
When you take a break from it however, like I do when I put down the gear and pick up the flyrod for months at a time, it can take a day or two to get yourself tuned in again back to the point you were before you set it down.
It will also set you back a few clicks when you switch rods, swap reels, or even refresh the line on your reel. Not to mention switching baits.
I can shoot a heavy jig, light jig, T-rigged tube, or a big 10" worm equally well.....but switching between either of those requires from 30 minutes to as much as 2 hours to get myself "tuned" again.
Dion and others that make a living at it do it darn near every day and they stay tuned 24/7/365.
He doesn't have to worry about wasting time idling 100 yards back to a certain dock and then "blowing it" with a bad shot that PINGS off a hoist arm or smacks the edge of a float, spooking every bass for 30 yards in all directions because he's tuned in before he ever even steps up on the deck. He doesn't have to start 4 docks away just to make sure he has it right before he gets to the money shot.
One misconception that a lot of guys have starting out is that they need to use the lightest bait they can get away with, and that's not at all true. Heavier baits give you more control and allow you to use the above water edges of a dock/cable/hoist as a fulcrum of sorts to control the trajectory of the bait as the momentum carries it to the target.
So it truly isn't as mysterious and complicated as it looks, but don't expect to be able to throw crankbaits or spooks, buzzbaits, ect. For 2-3 hours....and then expect to immediately pick up your pitchin rod and shoot a jig into a 4" crack 10-15' back under the dock confidently without making a bunch of racket and blowin' the first 10-20 shots. Ya gotta get yourself and your gear dialed in on a dock that doesn't mean anything to you BEFORE taking shots on the dock where you think a good fish should be.
Another thing to remember is that it seldom takes an amazing shot (as far back under there as you can possibly get it) to get the bite, so as much fun as it is to fire a bait WAAAAY back in there, there are gonna be times when that is not at all necessary. Times when getting it back just a few feet and doing it QUIETLY does the job just fine, or even better.
If you are shooting a row of shallow docks and notice that you are spooking turtles and cranes that are 2 docks away then it doesn't matter how far under those docks you can shoot a jig.
Just some things for y'all to chew on, hope it helps.