Oftentimes when doing something repeatedly, whether that be some sort of skill or action which needs to be learned over time, it can become sort of “mindless” as you gain familiarity with the subject. So even as you become familiar with the idea or concept, you no longer think about doing it even as you practice or utilize it more and more often. Because of this, some ideas can feel like they are more “drilled” than actually understood and comprehended, losing the sort of comprehensive fundamental knowledge that would come from a more complete understanding. If you just learn something to use as part of a larger project or system, then it can be very easy to develop an incomplete perception of the concept, and this is an area where I found the pattern “Record What You Learn” to be relevant.
Discussed in chapter 5 of Apprenticeship Patterns, https://learning.oreilly.com/library/view/apprenticeship-patterns/9780596806842/ch05s06.html, the concept of “Record What You Learn” is concerned with the idea of writing down or ideas, techniques and technologies/skills which you might use throughout the course of projects or development periods. Relative to software development, sometimes an application can be made up of many smaller pieces or technologies (ie: a web-application consisting of Vue.js, Express.js, REST-API, MongoDB, running in Docker) which you might need to become familiar and competent with during development quickly. However, needing to learn about many different technologies at once can leave gaps in your overall understanding, and you might end up needing to reference manuals or guides often.
The benefit of writing these things down becomes apparent when you can look back to your own notes or documentation and reference them in the future, and as opposed to simply looking into the documentation written by the maintainers or developers of the tool in question, your own personal notes will likely contain useful context and explanation which could be lacking from standard syntax guides or official websites. Maybe you find a way to save time working in C++, when you write that time-saving measure down it becomes far easier to repeat in the future.
If you constantly reference your own notes it helps to reinforce those ideas more than referencing something written by an external source because you are rereading your own thoughts and ideas relative to the concept. I have recorded notes for things I have been learning in the past (HTML/CSS and web-development, Java, C#) and I think that it makes a difference to have your own notes with added context. The connection to your thought process and ideas helps the concepts sink-in, and writing them down makes you think about them more than you might otherwise.