Depends on the rifle. If this is a production rifle, you will have to play with the sizing to see which works the best. BR guns are set up with very little tolerance and are as straight as can be. They also run fitted brass, etc, etc, etc.
In a "hunting" rifle, the action may have some slop or the chamber not perfectly concentric. Partial or FL sizing may give better results.
In general, I neck size as often as I can. I find this produces the most accurate ammo in general and longest brass life. I do not bump the shoulder leaving the fireformed brass as it comes from the chamber. I use the Lee collet neck die if available. I try to make the most concentric ammo I can.
When the case gets stiff to chamber (sometimes as high as 10 firings), I usually throw it out. By then, there are other wear related issues and sizing down can lead to head separation.
if you can get a commerical sizing die to just bump the shoulder and squeeze the base so that chambering is firm but not tight, you are a very lucky man. Chances are your buddy is using a custom die cut from the same reamer that cut his chamber. Big money and not always possible with a commerical rifle.
Try both neck and FL sizing and see which shoots the best in your rifle. Brass life may have to take second place.