After reviewing 20 close vote duplicates I got the "Thank you, come back in X hours" message. I'm curious as to why the number of hours varies. Yesterday I got one that said 6 hours and today it says 9. Why is this variable and how is it calculated?

I searched [meta.askubuntu.com] [2]  and [searched on S.E. Meta][1] and I couldn't find any related information.


[1]:http://meta.stackexchange.com/search?q=reviews+variable+time

[2]: http://meta.askubuntu.com/search?q=reviews+variable+time