Yes, but I only see facets of their performance. And I’m only interested in specific areas, and might be blind to other talents or issues. They might be the brightest bulb in the training class, but spend all their day reading hacker news and creating memes.

It’s very difficult to quantify individual performance, and even harder to put a dollar figure on it.

Re: experience and working hard vs. working on what the project needs, that's definitely a trait of more seasoned engineers. I'd say it's a matter of learning strategy over tactics. I've gotten pretty good at that balance over the years. When I came into my current project I focused on aspects of the software that had been sorely neglected before me, and plenty of folk where skeptical for the first year or so. Now in hindsight the results speak for themselves, and it's apparently become a story of legend that my coworkers tell new hires.

Last week I had fully intended to spend at least 20 hours heads down coding, but instead I spent the entire work week writing and updating an architecture document. It was the best use of my time, though, as it allowed two other people to be heads down coding instead. Now this week it's three of us frantically writing code instead of just me, and we all know the final result will work and be boring. We're replacing a 7 year old piece of critical infrastructure.

This is one of those things I stupidly thought I understood when I was a Jr. Engineer, and now understand quite a bit differently after decades have gone by.

The more competent people weren’t necessarily the ones getting more things done, or the most visible, but were those engineers who understood the long term implications of what they were building, how it related to the business, and their relationship to other teams and customers. It’s trivial to be a good “performer” toiling away on a feature or system that shouldn’t exist. It’s exponentially harder to have the awareness to identify where the real problems are, and make sure you’re investing effort where it actually needs to go.

Indeed. Experienced interviewers can size up a candidate in the first 10 minutes and fairly accurately predict how their debrief will go. The rest of the interviews are just building up confidence, and making sure there's enough redundancy to tolerate the occasional bungle or accidental awkwardness. Folk get hired all the time despite getting imperfect interviewer feedback. I've had interviews where the first 45 minutes were painful but then the candidate blew me away in the last 15 minutes.