Do you want to know how I know?
We just shredded a tote of papers and I found that the paperwork from the insurance company is significantly thicker than normal paper. I think they're in cahoots with the paper shredder companies. Because if you tried to put these things in 6 sheets at a time, you'd definitely need a new paper shredder, and I'll bet you would never think to buy insurance on that little machine.