In article <46nqb9$qgi@dartvax.dartmouth.edu>, jimmy.tung@dartmouth.edu says...
>Your black plastic envelopes must be stronger than mine. I've seen the
>envelopes start to become holed (in the corners after continuously
>being jammed back into a box or cardboard envelope) after being
>refolded maybe 20 times. Obviously, this isn't a real problem if
>you're using 25 sheets of 8x10, but it's reasonable if you use 100
>sheet or 250 sheet boxes. (...)

It is not necessary to take out sheets of printing paper sheet-by-sheet.
I take maybe 10 sheets out of the bag in the box, place them face down on top of the bagged paper, and close the box. When printing, it is easy and quick to open the box, grab a sheet, and close the box.
Hope this helps.