I don't bother. My backups are electronic. A number of independent systems, both certified and portable, would have to fail before I'd need to go to paper charts and, at that point, the paper would likely be far more useful for something other than flying an approachI have one of those, and I still print out plates and throw them in for the destination and alternate. Who knows when the ipad and foreflight are going to take a dump.
I figure since my iPad and EFB have not taken a dump on me in the 7+ years (well, my Stratus did overhear once when I was stupid enough to leave it on the glareshield, but that's a non-event) I've used one, I take the risk.