I am a young PhD-student who just started doing real research in mathematics. Of course, this starts with learning stuff which has already been investigated. If I try to understand for instance a paper someone wrote, I find it difficult to focus on the main aspects and ideas of the paper. Most of the time, I get stuck on some elementary details, which I had not thought about until I read them in that paper. Convincing myself that this detail is true is a matter of a few minutes, but the time adds up, so I end up losing quite a lot of time trying to understand details not directly related to the problem, but occurring in the solution of the problem. But if I skip this detail, I have the feeling that I did not really understand what the author is doing in the paper. On the other side, if I think about every detail, I lose my focus on the main aspects of the topic, which is not great either.
Conversely, if I work on my own problems, I tend to get stuck on minor details as well. Unfortunately, my advisor is not a good help in this regard.
My question is therefore the following, which can be also asked in other areas of research, not only in mathematics:
How does one find the right balance between focussing on the main aspects of a topic and the details, both in actual research and in trying to understand works of other people?