I would like to know what 事柄 adds to the sentence in terms of nuance (instead of more generic expressions such as こと、or もの, ...)
The context is of a veteran police inspector giving some advice to a new recruit on her first case.
あんたが教わってきた事柄は全て理詰めのセオリーだ それがどれだけ無意味なもんか すぐに思い知る羽目になるだろさ まあ覚悟だけはしておくんだな
Everything you've been taught is based on theories and logic. Soon, you'll likely come to realize how pointless they are. Well, at least be prepared.
「事柄」 here probably means "the content" you have been taught. The content can be abstract or concrete idea. Probably there are typical examples you have been taught and the veteran officer knows the pattern new recruit tends to fall into.
When you work as the police inspector, probably the one needs to improvise or using ad-lib on the spot in situations to situations rather than sticking to "armchair theory" you have learned.
So, the veteran police inspector would like to advise the new recruit the importance to be practical/creative/pliable, since 「事柄」: the "instances/examples/cases" you have been taught could be useless or it is not as linear as the formula you studied in the lecture.
