Imagine you are building a skyscraper. You have to have an overall framework drawing first. Then you will build the skyscraper step by step from the foundation. This is also how we learn. We learn new knowledge and adding it to the existing frame. Building a knowledge framework enables you to learn efficiently and effectively.
The first benefit a knowledge framework is that it helps with memorizing. With the explosive, fragmented information received everyday, it is easy to get lost in the sea of knowledge, and this is when we need a compass or a map which can help us locate where we are going and the optimal path. A knowledge map visualized the connection between different knowledges and therefore enables us to retrieve knowledge easily.
Second, you are building the skyscraper, you are reviewing what you already know. Every time you add new things to your framework, you will need to review the old knowledge and making connections to the new one.
Last but not least, when you have a framework, you can easily find your weakness. Since your knowledge is structured, it is easier to identify what causes the weakness. If you did not master some knowledge C, you may look back to the prerequisites A and B to see whehter you master them. You are able to tell whether your weakness comes from the unsolid foundation or not, so you can strengthen it quickly.
Not rush to the framework building once you get the textbook. A framework is different from your everyday notes: only with an overall view of the material, you can summarize it and frame it. Ask yourself, how is the new knowledge related to what I already know and how is it different? Then you may find an appropriate place in the framework for this new knowledge.
Once you have a framework, you can look into details. Breading down every point in the map into smaller points. On the one hand, it enhances your understanding of the topic. On the ther hand, it saves your time when you attributing your error. For example, when you find your inability to master knowledge C can be attribute to the weakness in prerequisite B1, you only need to strengthen B1 instead of all knowledge B.
Many students fall into the trap of creating a beautiful mindmap. Indeed, a written-down mindmap provides good guidence to crystalize your mind but it is only an assistance but not the purpose. So when you are framing the knowledge, make sure you are using your brain rather than copy down the menu, the titles and subtitles. Having the knowledge framework in your mind is the ultimate goal.