Quite a few comments imply that asking for something in writing is mark of distrust. I ask for things in writing because I often forget. Run into manager in kitchen and he or she asks a question. It's not like I had nothing to do, I was probably taking a break from another task I needed to finish. By the time I am done with task I was working on the corridor conversation is now blurred. So I need it in writing as a reminder. I could also meet two managers on my walk to get coffee and get to vague requests. I am that employee, if you want something from me put it in writing.