Some items break after striking a monster:
Other items can be used to kill an unlimited number of monsters:
A regular throw moves sideways, with a slight arc high enough to hit the ceiling if you're in a gap only one block high. Holding the up direction while throwing will launch the item upward at a 45 degree angle starting from the object's current location in your hands. Holding the down direction will do the opposite while jumping or holding a ladder, but will result in simply droping the item if not. Smaller items will bounce a bit when thrown into the floor, larger items are effectively dropped.