It's an idea that came to my mind today.
I saw book-recommendation tag and then I thought why not question-exam-recommendation tag.
This new tag would be very useful to summarize ALL the theory that you had to learn about $x$ topic, in other words you'll get the gist of the theory.
For instance let say Nemo is about to take an exam about Measure Theory.
And suppose he knows the exact themes $t_1,t_2,t_3$ that the professor is going to ask about.
And if he uses the new tag question-exam-recommendation among the topics $t_1,t_2,t_3$ in his question posted on MSE, then some people (maybe those that have taught the course) could help:
-Question $\lambda$ is a must be in a Measure Theory exam (including $t_2,t_3$ topic)
-Question $\beta$ is another very common question asked in a final exam (including $t_1$ topic) .
Can we create the tag?
I find this helpful.