One of the common reasons I have heard for hanging onto paper, is that the pile is too big to shred. If a filing system is purged regularly, every six to twelve months, it will be a more manageable shredding pile.
However if do have years of paper that needs to be shredded, I would recommend using a shredding company. Some will come out to you, and some will allow you to drop off.
Check the larger shredding company websites for community events, and schedule your annual shredding around an event in your neighbourhood. They usually ask for a donation towards the event’s charity of choice.