Semi
I have only needed it one time in many years - but I always want to have it available. Often I really do not even get to see if I got the hit until the smoke clears - then I do want to be ready - in case - so yep! I want the second shot available quickly.
Also I think since I am not working out of a stand, but stalking on the ground and normally in brush or timber it is something that makes me feel good to know I could/can get a second shot. Also because of the terrain I hunt in Idaho a run of 75-100 yards could put the animal in an awful big hole - not much is flat around here.
One other thing - shooting elk, especially a bull in the rut - you may not ever know if the first shot hit or not - they have a much bigger interest in their mind - pain is not always a factor.