The only way to really get better at sight reading is to practice regularly. You need to play new pieces every day. If you already played a piece more than 3 times it’s not sight reading anymore. Therefore, you need a lot of content to sight read pieces. Ideally, sight reading should be a regular part of your training routine at the piano.This second volume is not harder than the first one, but is instead focused on notes above and below the staff. Finding these notes usually takes a lot of counting. They don't often get memorized because they aren't used all that often. Especially those extreme ones.