At close range, most guys like to hold straight down the top flat of the oct/round barrels, seeing just the tip of the blade and putting that shiny spot on the target for zero. For 50 to 60 yards with the slow loads shot today, they see a bit more sight above the flat and maybe even part of the base, but still put the tip of the sight in the centre of the target. This 'sighting' is actually lowering the butt, which angles the barrel higher - same as raising your face does, as long as you put the blade on the target.
Now, if the gun is hitting high, low, one side or the other, bending the barrel to get it shooting 'to the sights', is the answer for many (if they want repeatable accuracy). You bend the barrel to get the ball travelling to where the sights are looking. Before doing anything like this, you have to be consistently shooting in the same place using exactly the same hold - comfortable & repeatable - a good group in other words. The barrel is then bent to put the group in the centre.
A 20 smoothie will shoot a 1" to 1 1/2" round hole for 5 shots at 25 yards - if you hold it the same each shot. In other works, they will shoot as well at 25 yards as most guys shoot their rifles. It is only past 25 yards, that the better shots with rifles have the advantage. Some shootbore shooters push rifle shooters even to 100 yards when shooting gongs targets. Shooting paper targets at 50 yards and beyond with 10-rings is another matter.