I've not found a clear answer to my question below. Everything I found on the internet was too fuzzy and vague, so I hope this is not a duplicate.
In which way does the word "quite" in front of an adjective strengthen or weaken the corresponding adjective?
Consider: "I'm quite good at school."
Does this mean I am very good at school, or like "good, but also not one of the best students" or even only considerably good?
The same for this: "I can run quite fast."
I've read, that this means that I can run not very fast, and I've also read that it means that I can run "very very fast, but not like Usain Bolt".