I don't know what you had in mind when you put in the timing functions (per question and per quiz) but it is useful. I thought I'd let you know that. There are psychologists that stress fluency of learning, which is associated with a framework called Precision Teaching, by which they mean response should not only be accurate, but also fast---almost automatic. The claim is that fluency decreases forgetting, decreases effects of distractions and enables easier incorporation into higher level skills. For example, kids who are fluent with multiplication tables have less difficulty with later math than kids who are not.
In any event, I have college students striving for fluency with technical concepts. Harris Quiz is set to present 60 (out of 100) questions with a quiz time limit of 5 min. The students take the quiz repeatedly and track their increases in number correct in the alloted time. Because the 60 questions are randomly selected from the 100 and the presentation order is random, simple order memorization is prevented.
I have just started using this technique and can't yet evaluate it, although students do improve across the repeated tests. The students seem to find it challenging.
I don't know if others use the time parameter (I haven't until now) but the effort to include it in Harris Quiz was worthwhile from my perspective. Just thought I'd let you know about this application in case your e-mail is light these days.

The best to you.

Coleman