These programming explanations are just concepts you can use to modify the stress-recovery-adaptation cycle. There aren't a lot of absolute rules about what you can and cannot do.
Novices do not typically terminate their novice progression for all exercises on the same day - usually one exercise moves to advanced novice, then another, then another, and then they move into intermediate one by one. I have a client right now who has intermediate programming for his squats, novice programming for his press and bench, and advanced novice programming for his deadlift. This is common.
On the other hand, keep in mind that we think about these concepts in terms of stress and recovery. So if you increase the stress on the squat, it may impact the deadlift as well. Typically, the stress from the squat and deadlift interact, and the stress from the bench and press interact. The stress from the press does not usually impact the squat much.
Again, these are just concepts. Not rules. I would recommend you finish reading the book, because these concepts are explained more and more using the templates later in the book. You may not need "2 steps forward, 1 step back" for your squat, but these concepts will become more clear to you if you learn about it.