Some office staff will remove stuff from window sills if asked and some will hardly bother to move themselves out of the way for you to get to a window in my experience.

Rather than removing paperwork etc. myself (which can add a lot of time to the job if having to be done a lot) I carry a dry towel or extra scrim to drape over so no drips go on there.
Easily done and won't add any extra time to the job.