I could write volumes about why I hate the particular textbook I am teaching from this semester, even though I am told it is very popular and widely used in Japan. (I'm using it because my students were halfway through it after last year.) But rather than go on and on about its myriad faults, I will share with you this one superlative example of the total randomness of this text.
In Chapter 21, the Translation and Grammatical Notes book lists the often used phrase shikata ga arimasen, which means "it can't be helped" or "nothing can be done", in the vocabulary section. It's definitely a key phrase for understanding the Japanese language, culture and psyche. But it does not appear even once in Chapter 21 in the main textbook. It's not in the example sentences, the conversation, the drills, the short conversations or anywhere else. What the hell is up with that? It can't be helped? I think it could have.