I have someone willing to write me a DO letter of rec, a guy I don't know super well but have talked to a few times. He's wondering how long the letter ought to be. I already have four letters from professors who know me well and another physician (my supervisor, an MD). I have been told that letters under a page or a page and a half in length can make you look bad, but since this letter is more to "check the box" for DO letter than anything else, is it alright if the letter is a bit shorter? The guy just doesn't know me that well and I don't want to have to ask him to write me more than a page.