There are bows that it is almost impossible to get it shooting true center shot and have the pins lined up because of torque.BUT what Art is saying is correct.These short a-a bows and highly reflexed 1 cam bows are HARD to get adjusted properly but MOST can be adjusted properly(some of the older magnesium riser are VERY hard to set up properly and in many cases require EXTREMELY stiff arrows).IT HAS TO BE DONE AT FULL DRAW.
To answer your question,center shot CAN NOT BE FOUND WITH PAPER.paper can be used to check your form,spine,and it is also useull in checking to some extent tune.If you ever move your arrow from centershot to acheive a bullet hole,THEN YOU NEED TO ADDRESS SOME OTHER ISSUES.
ps,My Protec is lined up straight down the middle of the pin.I tuned the bow,selected the spine and even had it rechecked on a shooting machine after I was done and was told I had it perfect.

As a result I get bulletholes.[

]