I agree that a bad batch of parts can happen, I understand that, what I take issue with, is the replacement of just the one valve spring, knowing they cannot identify which ones are bad. GM should do the same procedure on all engines that have the failure, and that is replace them all, so that I/we do not get to experience the issue, over and over. I begged the dealership to replace them all on the first failure, at 60 miles. GM would not allow them to do so.
This is my second bad experience with a GM product in the past 4 years (life long GM owner), the other was a 2016 Tahoe they never could fix. The dealership helped on that one, with a great deal on a trade in. I think, they did so, just to get it out of the service area, where it resided most of the time. I will say, the dealership has been great, and the reason I stayed with another GM product. I did not go with RAM, because I thought the GMC would be more reliable. Hopefully, it will be in the long run.
It was an 8/20 build. I would be cautious with any 6.2 built in the time frame of the TSB right now.