I have seen at many rest rooms, there are these paper dispensing machines, near the wash basins. Well, they are not machines, most of the time, but some things that have paper in them and you pull out papers to wipe after you have washed your hands. Many times people pull out not just one but two or three, papers at the same time.
Now just think if we could make every second paper in that machine slightly smaller, say by 10%. What difference does it make, for a stack of 100 wipes?
I am sure that most people pulling more than one paper are not really bothered about the size, as long as the difference is not significant. Assume that your standard paper size is 30cm, so now we have 3000cm of paper stacked. But if reduce every second paper by 10% we have 2850cm(57x50) of paper. That is close to 5 papers saved on the standard size, per 100.