Either way, they don't have to be cleared as you say, as long as the item you are recycling stacks with that item in the same spot in it's trash slots that it was designated to go to. You can have every trash slot filled and it will still work, assuming the item being recycled also designates the ...

This bug is easily reproducible but is particularly noticeable when using quality modules in your recycler. Simply setup a Recycler with 4 Legendary Quality Modules (though any rarity will do) and recycle Iron Chests. Have the Recycler output into an assembly machine that creates Iron Chests of the ...