When I write school papers (Essays and projects) I try to make it as succint as possible. I'll say this is my preferred style of writing. Compared to other students that like writing explicit write-ups. I want to inquire if it really matters if my school papers are as long as those other students? Will I get as much marks as those that wrote explicitly if we both cover the listed points?
Being concise is certainly a worthy goal. If you can convey an idea in 300 words that someone else takes 3000 words to express, that's a good thing.
On the other hand, if what you write is very short that might mean that you don't have very much to say, or that you didn't do the research to get all the relevant information, or that you didn't think through all the implications of what you're saying.
There's no way anyone can say, "The ideal length for a history paper is 20 pages" or whatever number. Like if you wrote a paper on the proper pronunciation of the name "Caesar", I'd probably be bored if it went more than a paragraph or two (though I'm sure there are linguists who could debate the subject for hours). "The Roman Empire" is a subject about which people have written many many books.
In a class room setting, usually you are given a target length. If the teacher says you are to write a 20 page paper, then I would turn in 20 pages. If I found that I could only get 10 pages of material on my subject, I'd broaden it, and if I was on page 50 and still going, I'd narrow the focus.
Never ever be afraid to edit. Bad writing is always full of unnecessary words and sentences. Take what you need to say and say it in as clear and concise a way as you can. Make no apologies for that. Any prof worth his salt will reward content, not length.