There is a school of thought that break and continue are just goto in disguise. It helps that these two are more limited in scope than goto and can be considered less evil. If you read the book Clean Code by Robert Martin (it should be required reading for all developers), you’ll see that he doesn’t like functions to be very long. I think his rule is no more than 4 lines. I try to keep mine around 10 or less with a hard stop at 20 unless it can’t be avoided because I’m switching over a large enum or something. If you put your loops into functions then you can just use return instead of break.
I did have a discussion with a teacher once about my use of early returns. This was when I had returned to school after many years as a professional programmer. I pointed out that my code has far less indentation than theirs and was simpler because of it and that it is common in the world outside of education. I got all of my points back he has deducted.
You’re going to hear some good and bad advice from your teachers. Once you have a job check out what the good developers are doing and just follow them.
I think the responder means that duplicate code is usually easy to refactor into single methods. Typically I see copy pasted code that is changed just a little bit. However much of a duplicated function can be broken into smaller functions and the redundant code removed in favor of calling into the functions. Often what is left then becomes easier to reason about and refactor accordingly. I love the PRs that I make which delete more code than I add but still manage to add functionality. It doesn’t happen often but it’s fun when it does.