Building using LFS has been on my list of "I really should probably do that just to learn" for about 20 years now. I'll get around to it! This year I'm finally learning Lisp (and really enjoying it).
Though back then, I learnt well from Gentoo by setting the system up from stage 1, which was a good knowledge to keep when trying to fix things such as handling partitions in single user mode or modprobe'ing to detect hardware and such.
If you can't do anything beyond relying on GUI, you could get stuck real fast.
I use it a lot for mapping out of the initial concepts but I find one of the best use cases is after understanding the basics, explaining where I need to learn more and asking for a book recommendation. The quality of my reading list has gone up 10x this way and I find myself working through multiple books a week.
Great for code too obviously, though still feels like early days there to me.