I never felt comfortable getting the set screws that tight, always thought that it couldn’t be good for the axle. Use axle collars, they work great. Next time you replace a bearing, look into SKF Concentra bearings. They are pricey, but worth it in my opinion. No more set screws to mark up the axle, and when it’s cleaned with brake cleaner and properly installed it will not move. I only have 2, and I use a regular bearing in the middle.