Linux from Scratch is great for building a deeper understanding of how the different parts in linux systems work together at their foundation. Working through it also made me appreciate what distributions and package managers actually provide to me even more. However, i do often read people stating it helped them to "understand linux". Not sure what that means to be frank. Because you do not learn much about actually doing things with or on linux. You learn, essentially, how to knock together a linux system from the various components, the core part being, setting up a compiler (if i remember correctly, you rebuild gcc three times in the process to get an "untainted" compiler), i.e. build something like a distro pre-cursor if you will. These are great skills to have, but also very specific ones. They aren't helping you much in your day to day use of linux. I think everyone serious about linux should do LFS at least once in their career (and, contrary to some popular statements, you actually can do it quite early on, if you can read and follow a manual), just maybe don't have false expectations about what it will actually be teaching you.