Wow reading this makes me thankful my deck is all composite and not wood. No sanding or staining or sealing or anything 
did you hear about the paper mill they’re building in Kuwait ?
they’re gonna make sand paper
Removing the screws, or finding the offending ones are both good ideas.
The problem is bigger than that though. There are two screws in each plank at one foot intervals. About one out of four of these is protruding. At the places where two boards meet, the contractor or builder drove the screws at an angle to catch wood underneath, and each of these four screws is protruding.
The screws themselves are for the most part, set where they are. You really can’t drive them or remove them any further. I’ve been using an air grinder to try and remove the offending screwlips with mixed success. I’m about 1/3 of the way done. Dropping from an 80 grit to a 50 grit Porter and Cable belt, and being as careful as I can be made each belt last about ten minutes on average.
I have about three more hours of sanding.
Sometimes what we do on an old weather beaten deck, is scrub it down with a weak solution of oxalic acid and then wash/rinse it real well. After drying, reseal or stain and seal.
You’d be surprised what that little acid bath bath can do to revitalize (in looks anyways) an old sun beat deck.
You don’t always have to resort to sanding.
As always, YMMV
I already powerwashed it, so it’s rough and splintery. Needs sanding.