It depends on many factors - tho there are some things that are indisputable:

1. Rifle must fit (when you shoulder it the sights are aligned without checking) and rifle is pointing at what you are looking atm
2. Your swing must be spotless (matching gun speed to that of the target without stopping when pulling the trigger is mandatory)

Inside 15-20m sights are superflous...the further out you get the more the focus moves from target to front sight.

It takes a lot to be proficient. It is one thing to shoot and try to hit the target, shooting to kill makes all the difference - to be consistent in doing it, shifts you to master class.