Question

Hello,
I recently happened to come across various long halakhic rulings.
For example, I saw a “pamphlet” about head covering and wigs that was 70 pages long, with dozens of opinions, stories, anecdotes, and more (I don’t remember exactly what was in it).
I saw another “pamphlet” about insects in food, and there too there were dozens of pages with opinions, reasonings, and various other things.
I study in a yeshiva and I’m thinking that maybe I want to study for the rabbinate and work in that field, and I don’t understand—does every issue in Jewish law have dozens of opinions, anecdotes, history, nuances, and so on that need to be studied? How is it possible to encompass all of Jewish law like that? How many such things are there? Hundreds? Thousands? More?
What I also don’t understand is that in anything in the world, if you haven’t lived it, you don’t really understand it. For example, someone who has never been in the United States or another country abroad won’t really understand the style of Judaism there, which is different from the style of Judaism in Israel. Another example: someone who hasn’t gone through things in marriage won’t really understand it, and so on.
Jewish law is basically a halakhic response to realities that occur in life, but how can someone issue a halakhic ruling if it’s possible that he thinks he understands the specific reality, but in fact he doesn’t understand it at all because he hasn’t lived it, or because of lack of knowledge, or for some other reason?
For example, a rabbi might rule that one is obligated to undergo orthopedic surgery if needed (makes sense, right?). But in my own specific case I have personal experience with this and know that there are surgeries that can be avoided through a number of specific actions related to muscle movement. So a rabbi who simply doesn’t know the field will give an incorrect ruling. And in this case that is something very significant.
That’s just an example—I don’t know whether it’s a good one or not. The point is: how can a rabbi issue a ruling if it’s possible that he doesn’t truly have a deep understanding of the specific reality? Moreover, it’s possible that he is not even aware that the specific reality is broader / deeper / has more nuances than he realizes. In other words, he thinks he understands, but in fact he doesn’t understand the specific reality.
Thank you very much