I never had a minimum-maximum range in any of my classes in undergrad and grad school. It was always a required number of pages or no requirement at all.
That's normally how it is, but in some of my classes the professor wants you to write a concise and dense paper, so they have a maximum page limit. It's actually annoying when you have you have a lot of content and the professor wants only 2 pages. Hell, I had to cheat and make a paper 11 point font once because I wrote too much.
I've had some classes where the professor would say you had to write exactly 12 pages; no less, no more, or you get points deducted.
and yeah, a 7 page difference. This one was 15 to 22 pages. The oddness of the number is what made me ask the question.