Are you letting it go, at length, doing anything more than a pilot assist does? I have gone > hour on pilot assist but that hardly qualifies as self driving and doesn’t free me from driving duties - which is what AP is supposed to do
The longest stretch I’ve used EAP for is >3 hrs going from MA to NY. Highways were totally smooth, did its own lane changes, etc.
It can be slightly jerky at times when the traffic keeps speeding up and slowing down sharply, that’s my only real complaint.