Generally speaking, this is an occurrance that is exceedingly common and extremely under-recognized in our industry.
Instead, he used the odd hours to force us to give him only
work that could be accomplished alone. We were lulled into
letting him make key architecture decisions in isolation
Eventually he became the architect by virtue of operating in
isolation, where we couldn't discuss his decisions. Everyone
else was forced to work around his code.
Our guy was genuinely, I think, the best engineer on a team of pretty good engineers. But in terms of sheer talent he was not a "10x" coder in terms of raw talent. Call him perhaps a "1.2x" or "1.5x" in terms of raw talent.
However, he was essentially able to operate as something like a "10x" talent because he got to do a lot of greenfield work, make sweeping architecture changes and decisions, and so forth. Meanwhile we were all left to deal with his fallout.
Whether or not you believe there are legitimate "10x" engineers (we'll set that debate aside for a moment) I think it is very, very obvious that we have misidentified the talent level of many engineers. Your actual output level as an engineer, be it 1x or 100x, is always a product of many factors and your actual talent level is only one of those factors.
Worse yet, having someone like that on the team drives away other great employees.
1. It's not a good way to make software, obviously. Great employees want to make great software and will be frustrated.
2. It's career fucking suicide to work under somebody like that. It's impossible to shine when working under somebody like that. You can't clean up a mess as quickly as other people can create a mess. You just can't. With very rare exceptions you simply cannot mop a floor well enough to be seen as something other than a janitor.