Looking for consistency, the least tension to hold the bullet in all circumstances, provides the most consistency.
Makes sense to me. One possible contributor is that less neck tension makes for less runout. When I'm using a bushing die, I try to find the bushing size that holds the bullet but allows me to move the bullet with finger pressure only. That's not zero, but close. Then drop down two thousandths.
That's not really a measure of tension, but it's as close I can can get and as close as I need.
