What you are actually learning, is not knowledge, it is consistency
Why is a PhD valued everywhere? The designation "Dr." respected and well-sought for?
Is it because of who they are? Or is it about what they had to go through to achieve that?
Why would you rely on one over the other? It's because they were consistent at what they did, and if your work is your baby then you will let someone else hold it only if you have an assurance that he/she would be reliable and endure enough to perform the task.
Not someone who can't stick in one place for even 3 months.
So when you are preparing for an exam, don't worry about the content, and when it would get finished. That's not why you are doing it.
You are doing it for one thing — building that consistency in you. So, don't worry if you are not moving ahead. Don't be demotivated that you are not getting the results. You are not in it for the results, you are in it for the process.
In order to get the results, your process should be right. So, just focus in nailing your process. The results will follow. And I think most people worry about the results because they are unsure about their own process, and try to see if there are "shortcuts" or an "easier" or "more feasible" way to do the same thing.
But honestly, if you delay it so much then even the most feasible way would fail you, simply because you didn't stick to it for long enough to work.
So, no matter what method you choose, ensure it matches with your value system and that you are ready to commit to it, and if you have even a faint idea that "this is the one". Then stick to it. Don't let go and just continue the process like how your future self would motivate you to if he did otherwise.