I have upgraded horn with relay. This is a new turn signal harness so surprised it wore out so quick. I have seen the mopar ones with rollers and wonder why these are not. Stupid design. Aftermarket has failed this one.
Needs something like ball point or roller pogo pin at the end. or really needs to be more of a flat slip ring design. which i think all newer cars use.
If you use the lube that comes with the kit, it really does work.
As for rounded or roller, electrically they suck and you have point contact instead of surface contact. You will erode tiny pin holes in the copper and it will fail worse/sooner.
Stock contacts and copper slip ring will last the life of the vehicle, or at least the turn signal switch,
If you wanted to be really trick about it, change the copper contacts to carbon. Like a set of brushes in an alternator.
As for what new cars use, spiral wire. No brushes. Very high failure rate. The ribbon cable spiral wrapped fatigues and breaks. But you need the spiral cable for the airbag to work. When the wire breaks it, it goes from good to failed, not an intermittent contact. That makes firing the airbag and diagnosing the circuit much more solid.