How can I get better (and develop an art style) at drawing when no matter how much I practice it doesn't help?

Practices, rest ( go wandering around untill your mind reset ), practices again, try new idea from other pro, feel the comfort, when you feel burdened, go rest ( start wandering around again ), then practices again.

The more you draw, the more you think and draw so hard to reach perfection, you will advance.

You see, when someone reach some treshold, somehow the improvement become sluggish, not because it not improve, it because the more level you gain, the more dificult to advance.

Or, you gain burden. Overcome your burden.