Apparently, this wasn't GM's best V6. Far from it, in fact
We have access to the GM factory website at work, and over the years, I have seen a LOT of information about that engine. Campaigns, customer satisfaction, recall, tsbs, etc.
And it seems this engine has had some serious mechanical problems, right from the start, all the way through the end of production. And it's not just the chains wearing out
I agree that the chain shop wasn't the best choice for this particular repair. This is probably way more complicated, versus their more typical brake jobs, tires and ac recharges
That particular shop should never have agreed to the repair. Auto repair shops . . . and other businesses, for that matter . . . do occasionally turn away work, and often for very good reasons. It's important to be able to recognize when you're not set up to do a job, whatever the exact reason may be
And yes, the learning curve can be quite steep. Every mechanic has had a first time for certain types of jobs, and they probably took longer, and/or made mistakes. It doesn't necessarily mean the guy is incompetent. It means he's human. Now, if he makes the exact same mistakes time and time again, maybe it's time to let him go, because he can't or won't learn. Or you could do what some service managers, dispatchers, etc. do, which is to take steps that certain mechanics NEVER get assigned the more difficult repairs. That last one has its pros and cons, though