I'm approaching trad archery from a bullseye rifle/pistol shooting background. I've only been shooting (trad) for my third summer.
With that, I feel that any shooting sport is as much mental as it is physical. There is a lot you can do to "train the brain" when you can train the muscles.
The USMC has a proud tradition of producing exceptional nationally-ranked bullseye pistol shooters -2700 course of fire: rimfire/ centerfire/ .45. One of the training components they do, and it is in their training manual, is to do the equivalent of "blank bale shooting." They stress dry firing with your pistol at a blank sheet of paper on a wall at some close distance ; ie 5 feet? 10 feet? doesn't matter. The idea is to learn trigger control, sight alignment, and follow through by watching the front/rear sights -with emphasis on the front sight- as how it looks before, during and after the "shot." I forget the exact percentage of time practicing like this, but it is well over 50% of the time. Live fire was much lower than I expected to learn about-but I THINK it was in the 35% level of total time "practicing." Dry firing at a blank white sheet of paper also allows you to learn the very fine details of the trigger release -roll edge trigger sear or "ninety degree" "breaks like icicle" sear. The point is to notice the nuances of the pistol. The overall point is that live shooting is only part of the practice.
I think this can be applied to archery. Of course you can't dry fire a bow, but you can certainly go through a mental shot form sequence. You can "blank bale" shoot with just pulling your fingers -like a deep hook- across your chest to simulate drawing, holding, developing back tension, and then releasing to have your draw arm recoil back like a spring. Builds strength.
I don't see why bow shooters just don't hold their bow in their bow arm and look down their bow arm with an unstrung bow, but with an arrow on the rest and you holding the nock back at your anchor point. You develop your bow arm muscles this way, and also gain familiarity of the nuance of the bow's grip. You also can have a dot on the wall 5 feet away and hold on it in this manner to minimize "wobble" and make bow arm more stable / stronger. A right handed pistol shooter holds the bow in the left hand. If you are a right hander, have you ever tried to shoot a pistol with your left hand? Pretty ugly for most of us. We need to make our left hand/ arm "accurate." We need to train it and work it. Don't need to shoot to do that.
Then, there is a "standard" pistol shot / grip analysis chart on line you can google. It analyzes why a bullet hit a target at at certain place. heel pushing up? fingers pulling to one side? Thumb involvement? Limp wrist etc. The forces of a bow string releasing is substantial. I wonder why more isn't discussed about bow grip and accuracy in archery. Ok, there is "bow jumping forward", and angling your knuckles out 45 degrees -etc. But, there is still a time element of bow /hand contact that can affect arrow flight as variable/non-consistent forces are applied to the bow during release -and until the arrow clears the riser. Just something to thing about. Hold the bow our at arm's length, not drawing string, can have benefits-and can be done just about anywhere. Heck , I'd even wager that getting an accurate, inexpensive .177" pellet pistol and shooting it with your left hand in your basement -into a trap- would be a benefit to improving archer accuracy for right handed shooters. That can be done year 'round, and in the basement. Even dry firing an unloaded pistol with your left hand at a blank sheet of paper on the wall will develop bow arm muscles -large and fine control.
Then, shoot arrows as ofen as you can-whether it be daily, weekly or monthly. You can only shoot when you can shoot, but you can do the other "dry"/ non-shooting drills just about anywhere/anytime.
Elastic bands/surgical tubing can provide draw arm muscle toning/ back tension.
Very few can shoot as often as then want to, but maybe shooting all the time doesn't help, if you don't have other components maximized in the shot sequence.
You can also "train the brain" simply be estimating distances to things you see daily. Is that filing cabinet 17 yards away? 21?
Anything you can do with repetition will help you.
Again, this is from an archery noob, but a decent rifle/pistol bullseye shooter.
Good luck. Not trying to be an "expert", just offering a different take on training. It's not just shooting arrows or bullets.