Not sure what style DC you have but mine is round bar with 1000k bars. The bores the bars slide in on the hitch head can wear as well as the contact point on the bars. The saddles and portion on load bar that ride in the saddle wear also. I have had mine since 05 and it seems to wear evenly. Any slight wear mine has makes no difference. If anything eventually I may have to provide more tilt on the head from bars fitting looser in the bore. With friction comes wear but it would take a long time to wear one out completely.
The area on the round bars that need to be checked periodically are the grooves in the top of the bars that keep them from falling out of the hitch head. I have read other posts where they have cracked. IMO there should be a pin as a failsafe as well.