Joe replaced all of the rockers and lifters on the passenger side with new Mopar parts. i had one rocker that was completely toast, and a couple more that were just starting to get loose.
the bearings in the rocker arms just seem to disintegrate over time, then you get a sloppy roller on the arm that is smacking around and you hear a ticking sound. you also get poor performance or even a misfire DTC since a valve isn't opening completely. the bearing failure lets the edges of the rocker arm eat grooves into the edges of the cam lobe, but the camshaft is still usually salvageable in that case. however, eventually the roller will freeze up and then it wears away the entire width of the cam lobe and you need a new camshaft.
the problem can occur any time, though it seems to happen more often on high mileage vehicles from my casual research. i think it happened to me the first time at under 20k miles, and Joe has also seen it on rigs in the 20k mile range. i don't know if it's still happening on the 3rd Gen 3.6L that's in the JL/JT platform or not, but apparently that engine has quite a few design differences. no-one has offered any theories as to why it happens to some people's engines more often than others.
the current Mopar part number for the rockers ends with "AH" - meaning they've revised the design or changed manufactures 8 times!
no-one seems to have a proven long-term solution. there's no aftermarket rockers that claim a better or even different design, no add-ons to direct oil onto them differently, just nothing really.
Joe suggests that it may help to do 3k mile oil changes using a thinner 0w20 weight synthetic oil along with Mopar filters and overfilling a 1/4 to 1/2 quart. i've been doing all of that for a while and still had the problem... though mine could have started wearing out before i switched to his recommendations. i always had the dealer do the oil changes at 5k mile intervals beforehand. i've never missed or prolonged any service interval.
i think this was my 4th time needing one or more rocker arms replaced. the first time Jeep gave me an entire new head assembly on one side. after that i think they only replaced the actual worn-out rocker arms and lifters each time under warranty. Joe always replaces all of the arms and lifters on whichever head he has to get into. i don't remember which times were in which head previously, but this time it was the passenger side.
sorry for the long response, hopefully it helps other people that might be looking for answers.