If you sew on paper:

You need to keep track of those needles. Machine needles are sharp and paper has grit in it- enough to dull your needle (and enough to scratch your glasses if you use a Kleenex to wipe them). 

My solution is to write on one of my pin cushions to indicate where I am keeping each used needle. I added a section for "paper needles" today. This way, I can save the dull needles for that task.