That second perspective would come from whom? The same guys would be conducting both interviews. You mean there are key questions they forgot to ask the first time?
Personally my experience is you lose too many winners to other competitors (see this year’s actual results). People looking for jobs typically can be persuaded to take a great offer. How do you think so many guys already got committed? In this case if you hire a guy who takes 6 months to learn the business or suggests blowing up the team; you hired the wrong guy. That’s why you ask questions. That’s why you ask them to analyze your roster.
As to that guy you’ve nutured, if he doesn’t interview head & shoulders above the rest; you’ve nutured the wrong guy. Finally if you think hiring the right coordinators assures a head coach of success you have quite a bit of faith in people staying in their own lanes as Keim would say. I’m not certain any big time coordinators are dying for a chance to work for Bettcher. My experience is the top guy better be the best guy. I know people say they win by surrounding themselves with a great staff. However, if those guys underneath learn their better than the guy on top; they’re leaving to be the top elsewhere. The best leaders are the top dog. Ask Belicheck!
The second perspective just means a second chance to interview. Now with a better idea of who the others are, and what their gameplan is. You also bring the other candidates into the office for the team to meet them, and see how they interact with that environment. What if they're awkward and lack confidence? What if they're too cocky? (All using this as a business perspective again.) Everyone brings different skillsets and concepts - there is no one "true" answer of who the best candidate is, as you can't predict the future. A person's presentation skills and resume may look great, but they may be terrible at executing. That's why you don't get enamored with the shiny toy and do your due diligence.
My 6 months number is what my organization uses as a general timeline for when we believe they will have themselves up to speed with the business, and up to speed with the employees they report to. A new coach is literally going to have about 6 months to hire his coaches, install the system, and have the team ready to go by the start of the season, and that's the best case scenario. BA's offense, and Bowles' defense, really took about half a season to "click" with the players. Not to mention, guys have to buy into the system, and like it or not, there's going to be turnover in the roster depending on what a completely new coach is going to do.
The nurtured guy is a known quantity. You know his work ethic, you know how the players and team reacts to him, you know he's not going to need to take 6 months or more to teach new concepts to the team, or determine who on the roster fits his philosophy or doesn't. I've been promoted twice within my current organization - but let's make no bones about it, there were probably some other "more qualified" people out there. However, I have chemistry with my organization and know my responsibilities inside and out, which is valid and important.
Don't get me wrong, I'm not amped about Bettcher, but the sky isn't falling throughout this process.