Originally Posted by
rugerpc
Generally a screw looses its hold because the hole is stripped axially, not lengthwise. That is because the hole is too large in diameter for the screw threads to bite into the wood, not because the hole is too long for the screw.
So placing pieces only at the bottom of the hole only solves the problem to the height of those pieces. You need to reduce the diameter of the hole for it's entire length (depth).
If you don't want to completely obturate the hole and start over by drilling a pilot hole, try using several slivers of toothpick which are in total smaller than the diameter of the hole. You should glue them, but you don't have to - it just won't be as strong a repair.
You will know you have enough slivers in the hole (for it's entire length) when the screw feels like it has more resistance to turning and feels like it is biting into the toothpick slivers.