At my office we receive tons of faxes every day and most people use a cover sheet. I keep a folder near the machine and if there's no personal patient info on the cover sheet, the staff saves all the cover sheets for me. I also use the exam table paper if I'm tracing large pp blocks that won't print on my printer.
To illustrate how much paper is wasted: we were off for a long 5 day week-end. When we came back to the office there were hundreds of faxes on the machine. At the end of that just one day, I had over an inch of cover sheets!