i don't really know the answer, i would guess that it is less strain on the animal to regenerate a tail that takes less energy to create. most of the leaftail regerations i've seen however mimic the original much better than that of say an anole. i'm watching one of my lineatus regrow its tail right now and it is VERY strange looking. it seems to regrow the main vein down the middle of the tail first, then the sides come in. there's a stump about 1/2 an inch long with nothing on the sides and it looks just like a vein growing out of the end of it.