There could come a time when the second shot will need to be taken kinda quickly. One wouldn't wish to clean, clean, and re-clean the barrel, before reloading.
Myself, for years i hunted with a clean clean barrel, and found the second shot usually was real real close to the first shot. However, in some rifles, the first shot is all by it's lonesome. Lately, i have taken to popping 3 primer before i load my hunting rifle the first time. The primer residue is non-corrosive. This seems to bring the first, second, third, fourth.........................shots to about the same spot.