I forgot to mention...

Of course all of that has to coincide with having the proper neck tension to hold the bullet in the case. As others mentioned, about 1diameter is plenty to hold securely.

If you try to seat to say, 0.020" off of the lands, but you only have 1/4dia in your neck (VLD type bullets), then your chamber isn't suited for that bullet. New bullets are cheaper than new barrels. (again, an exaggeration).