The usability of a plain copper tip is also highly dependent on its actual tip profile. A hoof tip, tinned on the face and its edges only and oxidised and oiled on the sides (with a high temperature drying vegetable oil) to form a protective coating, can easily be dressed with a file or stone to eliminate pitting then immediately retinned. Of course it needs excess length in the first place to remain usable after repeated dressing.
A chisel or knife bit is more problematic as it needs at least two faces dressed, and pitting will tend to erode the corners and edges. A conical bit is even more problematic as one tends to get large cavities in the sides near the tip, and they cant be dressed keeping the profile without removing a large amount of metal on all side.
Another issue affecting the rate of pitting is how aggressive the flux is, and if the iron is use infrequently, one should avoid corrosive fluxes.