As an academic researcher in mathematics, I would say that people who understand a lot, very fast, are incredibly rare.
IMHO, society has formulated the stereotype of a mathematician being an extraordinarily clever person. While it may or may not be accurate, this leaves out the element of ~~immensely~~ ***hard work***, which makes mathematicians almost unrelatable.
You see, in movies there is always numbers, in golden colour, cinematically dancing around inside the minds of talented mathematicians. We, as viewers, see that and secretly think "well... since I can't do that, I guess I do not have the talent to be a mathematician". To that end, I believe (and people are welcome to correct me if I am wrong) that this almost never happens to anyone.
This might sound like a pep talk, but what I want to say is the following: Do not care about how much or how less something takes for you to understand this. *If it looks interesting, spend some time on it. If not, maybe you can do that some other time. It really is as simple as that.*
Edit: Spelling errors kill people.