When I was preparing for the IIT JEE exam, there were two popular books for physics: HC Verma (HCV) and Halliday, Krane, and Resnick. HCV had all the answers to the questions at the back. Solving those questions and cross-checking the answers gave a quick dopamine hit, and then you moved on to the next problem. On the other hand, Halliday, Krane, and Resnick only had answers to even or odd questions, which means you couldn't cross-check at least half of the questions.
I was pretty puzzled by this. Growing up, I have only seen textbooks with all the answers at the back. I asked my friend about this, and he told me it's designed that way so that you can build confidence in your approach and steps without knowing whether your answer matches the author's answer, and you discuss those things with your peers, teachers and keep those questions in your mind and keep thinking about them. I just moved on then, only focusing on questions I can verify.
Fast forward to my 5th year at college, I was lucky to have saved a lot of money, and I was waiting for placements to be over before I started investing that money. Luckily, COVID happened a few months after my placements, and I got a bunch of stocks at a discount. By summers, I had invested all my surplus funds and checked market prices daily, looking for that validation of whether I was correct or not. It's as if I solved the question of "what's the best portfolio", and I was looking for answers at the back of the textbook. That's when reality hit that after schooling/education is over, there are no answers at the back of the textbook. I was left to figure out whether the process I used was appropriate. I talked to peers and others about it, and that question was always at the back of my mind. I kept looking for things that either validated or invalidated my hypothesis.
It took a long time to unlearn seeking quick validation, whether I am correct or not, when none was available. I certainly wish I had learned it earlier.