You learn best when you’re stretching yourself beyond your previous level of comfort.
Sure, getting into a routine is great. “Flow” is great too. But neither is the best way to learn. You want to be stretched to the edge of your ability sometimes. It needs to be hard and uncomfortable. That’s how your brain grows. We learn when we’re in our discomfort zone.
When you’re struggling, that’s when you’re growing stronger and smarter. The more time you spend there, the faster you learn. It’s better to spend an extremely high quality ten minutes growing, than it is to spend a mediocre hour running in place. You want to practice at the point where you are on the edge of your ability, stretching yourself over and over again, making mistakes, stumbling, learning from those mistakes and stretching yourself even farther.