D335 Sections of Zybooks to focus on?

Taking the SQL programming course earlier this year the first two sections of Zybooks out of I believe a dozen or so units was what nearly the entire OA was focused around. I am currently in the Python course and wondering where most of my time should be spent geared towards studying or if my time is being wasted focused on studying things that do not make it to the OA. Any guidance would be appreciated.