Bonus durability when repairing items though a grindstone

The grindstone has 2 input slots, but the second slot is almost never used since you can do the exact same thing in a crafting grid.
When you combine items in a crafting grid or a grindstone, you get 5% more durability in addition to the durability of the current items.

So my idea for the grindstone is that if you use it instead of a crafting grid, the bonus durability will be higher.