When a case is sized, the neck is reduced in size, and then it is pulled over the expander ball. If the difference between the inside diameter of the neck (before it goes over the ball) and the expander ball is large enough, it creates so much pull that the shoulder of the case deforms from the pull, and because it does not do so evenly, the case neck is cocked in relation to the CL of the body of the case. If you increase the ID of the neck portion of the die, the inside of the case neck is only slightly larger than the expander, so that it does not take very much force to pull the expander through the neck. The shoulder does not yield, and the neck stays as aligned with the body as it was before expanding. Tips about polishing expanders and lubing the inside of necks help, but having the ID of the neck part of the die larger is much more effective. FYI Forster offers this service for their dies, for a very small fee, and for quite a bit more Hornady will make you a custom die, to your specifications.
In short range benchrest, which I practice for more than compete in these days, the pressures that are commonly loaded to are hot enough that most shooters prefer to FL size after every firing, so that the position of the rifle on the bags will not be disturbed by having to force the bolt closed, and the risk of galling locking lugs is reduced. I should add that if you have never used a closely fitted Fl die, you probably associate FL sizing with all sorts of evils that are not a problem with the dies that we use. It is most definitely not a chamber design issue, but rather a pressure issue. Recreational shooters may look at barrel life, case life, and convenience. Competition shooters (at least the short range crowd) are concerned about one thing....accuracy, and if that comes at a cost (reduced brass and barrel life), then that is the cost of being competitive. Actually, because my die is such a close fit, my brass lasts a very long time, but then I generally shoot load that are only hot, not very hot. If you can get away with only neck sizing, for a number of firings, your load pressures pretty much have to be moderate, and it they meet your goals ( I have seen some very accurate loads that did not generate high pressures.) then there is no issue.