I used an adjunct who only taught one class a semester for one of my LORs. He had me read it to make sure it said everything I wanted to say (I know you're not supposed to do this, but who wouldn't if given the chance, seriously?). It was by far the best LOR I could have hoped for, because he really got to know me and what I believed in, and my academic abilities and downfalls. I didn't have to ask him to change or add anything.