It's nice to know we weren't the only ones who inherited decade+ old documents that needed attention
Our clerk was the only holdover when the rest of us newbies were called, and he was patient as we got settled with more pressing matters, and then finally prioritized data cleanup (in a smaller unit, it can be challenging just to keep your head above water, let alone make repairs to the ship). And it definitely took us a while. Almost as lengthy as the disposal, was the sheet-by-sheet review we decided to perform. There didn't end up being a lot of papers we retained, but we did find (sometimes randomly mixed into other groupings), a number of historical docs that we decided were worth keeping. A few we digitized and even made part of the unit history (building open house, building dedicatory prayer, etc), that nobody knew even existed. Other items like baptismal programs we gave to those members as keepsakes, and they were surprised and grateful for our efforts. And since I'm a bit of a history nerd, it was interesting to see some old church hq letters with different instructions, and consider how things have changed over the years...
It probably took us about a year to get fully through the shredding, and also the disposal of old manuals/booklets. We chose to simply ask the clerk to take a few minutes every time he was at church, and chip away in very small bites. Although daunting at first, when we just added a couple of minutes into each "church workday", it ended up not being overwhelming.