Even if the goal is clear and achievable, it is still not enough. You need to know where to find the information you need.
For example, if you knew that there is a stationery shop where you walked a bit from your house, you can go there to buy stationery when you need it. You do not need to know in advance the items of the stationery store or the arrangement of the items in the store. If you grasp that there is much stationery, you can go there and watch the shelves when you need it.
The same is true for information. For example, you do not need to know all function names in advance for various libraries in programming languages. If you grasp where you can get detailed information, such as a website, you can open the website and watch it when you need it.
It is a bad goal to know everything in detail. The goal of knowing everything in detail is so far away. It is doubtful that it is possible.
It is a reckless goal to try to grasp the arrangement of the goods of all stores in the world. It is the same. First of all, you need to know what kind of shops are. And then, create a rough map of where they are. After that, you can gradually make them detailed.
I tell more about how to grasp the overall picture roughly at the next section (1.3.3) Learn roughly first.