I do the same as Mark and cut 50 or so sheets are a time on my rotary cutter. Since I like borderless prints I usually don't worry about the size too much as long as the sheet is "long enough." I then cut the print to size after I am finished processing it. The only real difference in my process is that I unroll, say, 20 feet from the roll and put the rest back in the box just in case lights would get turned on so only that much paper would be spoiled. I don't worry about any waste that much - I just use it for smaller pieces. After cutting the sheets are stored in a paper safe of a light proof bag.