Tacking caps on stock shafts vs tacking caps on chrome Molly shafts are two different things. With the stock shaft and allowing the cap to rotate via the snap ring will tear up the hole and egg it out. I haven't seen this effect on chrome Molly shafts because the metal is stronger and the cap spinning doesn't have the same effect.
IMO tacking caps on chrome Molly shafts is pointless. But with factory shafts I have noticed an increadable increase in the life of my axle shafts whether it was my d35 ttb, 44's or my current 60. Every time I tried full circle clips the ears egged on stock parts.