This idea of skill through practice is one of those values that I am very grateful for because it was sort of drilled into my head at an early age and has been enormous beneficial to me throughout my life. It's become more valuable now that I'm older and don't absorb new information as quickly or easily.
"From Sato," Tõzan replied.
"Where were you during the summer?"
"Well, I was at the monastery of Hõzu, south of the lake."
"When did you leave there," Unmon asked.
"On August 25" was Tõzan's reply.
"I spare you sixty blows," Unmon said.
The next day Tõzan came to Unmon and said, "Yesterday you said you spared me sixty blows.
I beg to ask you, where was I at fault?"
"Oh, you rice bag!" shouted Unmon. "What makes you wander about, now west of the river, now south of the lake?"
Tõzan thereupon came to a mighty enlightenment experience.
Zen tales tend to present a couple major challenges to the reader:
1) Going into them cold isn't exactly intended. The characters are usually named for a reason, and it's expected that the reader/hearer will already know some things about the historical persons in the story, possibly some other tales about them, from reading histories and lineages, and so on, providing more context than is apparent at first if you take the stories per se.
2) There's often at least one relatively easy-to-pick-out though rarely explicitly stated lesson in them, but also one or more metaphorical or allegorical readings, at least one of which will be a "canonical" reading, i.e. your teacher will expect you to come up with it after some consideration before moving on to the next koan/tale—they don't expect that every student, or even many, will come up with a totally new and valuable metaphorical/obscure insight to the koans they present them, as that's just not realistic and no-one would ever advance if that were the expectation.
An easy example of 2 is (from memory so this wording will suck compared to the real thing) the "what should I do now?" "have you eaten your rice" "yes" "then clean out your bowl" one from (IIRC) Gateless Gate—simple surface reading of first-things-first and the importance of routine-following, but one available deeper reading of this as a Zen "challenge" (many of the koans/tales are) where the question "have you eaten your rice?" is actually asking, as understood by both characters, "have you attained enlightenment?" or similar, and "then clean out your bowl" has to do with banishing hubris or something along those lines.
Point 2 especially fairly speculative and arrived at purely second hand—I've not practiced Zen Buddhism—though I'm confident enough in it to present it here. Take that for whatever it's worth.
[EDIT] further, the point of their contemplation is in taking the journey to the answers, in part for the value of the journey and (one supposes) in part to train in the kind of lateral thinking that's so vital to these "zen battles". So just having a list of "answers" alongside the text kind of defeats the purpose, though they're definitely not intended to be as obscure and hard to follow as they are if you go into them with no background on (basically) Buddhist historical trivia.
I'd add that a lot of the stories are challenges in the sense of asking "What kind of mind must the characters have to give these kinds of answers?" There's usually a sense in which the interaction feels most natural.
In a way they are like inside jokes. Once you get it, there's little question about the meaning, and usually there's no need for any philosophical sophistication. In my experience, a good bit of The Gateless Gate is uncouth humor.
The teacher then gets angry because the student tries too hard to understand by questioning the teacher rather than trying to work out their own answer or accepting the state of things.
The correct "answer" to the question then (so far as there is one) is to place yourself in the story and either accept it as it is, or come up with an interpretation of the story (like this).
The wrong answer is to ask what the answer is.
Then I definitely lost this one myself.
And the physical disciplinary punishments are brutal.
Oh and you have to keep this up for 5-10 years. Very reasonable to see why someone would not want to commit to this.
Many of the warrior monks were trained as very young children so they had not much say in the situation and just had to deal with it.