Looking through barrel and scope on a spot on the wall is just to get on paper faster. Not really a serious q.
But I do something similar.
I have a laser level for work that has cross hair , I put directly under the barrel and point it where the barrel is pointing.
I also level my scope this way and then dial the scope on the +
Usually pretty close to dead center at 25 yards when I go sight the scope in.
Then just set the target up further
