I never had that requirement outside the first years of school- where it’s more about writing practice than writing actual essays. After it was always “must be below X pages”

X words is supposed to be a proxy for do enough research that you have something to say with depth. A history of the world in 15 minutes better cover enough ground to be worth 15 minutes - as opposed to 1 minute and then filler words. Of course filler is something everyone who writes such a thing and comes up a few words short does - but you are supposed to go find something more to say.

I eventually flipped from moaning about word count minimums to whining about conference page limits but it took a long, long time- well into grad school. The change came when I finally had something to say.

When I was a lazy kid, and there was a requirement to fill a number of lines/pages, I'd just write with bigger letters.