While studying math, I usually get stuck on some topics, how long should I insist trying to understand it alone? What are the strategies for when this happens?
This is an answer that is based on my opinion and not necessarily fact.
It really does depend on what the topic/problem is. In general I would say that it is best to keep trying, but if you are able to identify a part of the topic/problem that is causing you problems, I would say that you just go ask someone. And when you ask someone, you can always try to ask for hints instead of complete answers.
As an example. If I am reading a paper, and there is a part of the paper that assumes that you know something about for example measure theory, and I don't know much about that, I would definitely just go ask someone for help. Maybe just ask someone for a crash course in say measure theory.
However, if you are working on solving an equation where it is just the arithmetic that is causing you problems, then I probably would just keep trying.
What are the strategies to "keep trying"? You might simply take a break from the problem for a while and come back later. If the problem is simple arithmetic, then you could also try to step back and try to for example write down all the rules/methods of arithmetic that you can think off. Then go over each rule/method and see if applying that in some way might help.