How much medical paperwork (from Medicare, insurance co., etc.) do you save?

I now do the finances for my parents and the amount of mail they receive from Medicare, Supplemental insurance, doctors, etc..is staggering...I don't know how my poor mother did it! How long do you keep the Medicare Summaries and the EOBs from supplemental insurance? They also get a monthly report from their prescription program. I was thinking just keep a years worth of everything and then shred it? Thanks