As the joke goes, one morning Livshitz was riding a tram to work, someone pushed him and he dropped his manuscript into the mud, ruining a few pages. When he arrived at the lab, he complained to Landau that he would have to spend the whole day rewriting the proof of a tricky theorem because the middle part was now gone, but Landau suggested simply to put "from which it is obvious that" there instead.
In undergrad I took a graduate class out of Calculus of Variations by Gelfand and Fomin [0] that went deep into the math of classical mechanics but assumed students already knew the relevant physics. I hadn't taken a proper classical mechanics class, and working through Volume 1 of Livshitz-Landau in parallel with the lectures helped to ground the material for me. A brilliant classmate who’s now a successful mathematical physicist had recommended the series.
Later I tried to learn Quantum Mechanics while taking a course on Operator Theory, but gave up on using Volume 3 of Livshitz-Landau because it was just too impenetrable. I ended up going with Sakurai instead.
I found Volume 1 to be beautiful read and felt like I was learning something profound. Volume 3 was beyond me. The only thing I'd say these books have in common with the Feynman Lectures is a dearth of exercises. This wasn't an issue for me reading Volume 1 of LL because that Calculus of Variations course had many exercises which I just wasn't in a position to appreciate without knowing more Physics.
Accurate. I had a immigrant Russian professor in undergrad QM whom provided no notes, I could barely understand anything he said, and he just said to use L&L as the course book when people asked for help. I spent hours trying to read it but it was utterly useless. Worst studying experience I ever had