I read the optional stuff if it looks interesting.
I only read the optional stuff if i have the time, but now i just concentrate on the LOS’s…
Some portions from CFAI are quite good, but some are very long and you tend to miss the point totally. This is where Schweser is good. Most of what they cover is precise and crisp, but they may not be covering 100%. If you have time and energy, you could search for good portions from CFAI and schweser/stalla. If not, just do either one of them, whichever you feel suites you better.