[SilasX]

I think there's "10x" and then there's real 10x.

Fake 10x: Turns out lots of stuff quickly but it crumples under edge cases and has non-obvious tight couplings that keep biting you. No one else can make changes to their code. None of their stuff can really be used when they leave the company, but they can fix it really fast.

Real 10x: Is able to explain what they did and why bugs happened. Easy to follow along in their code, you get the impression the job was easy. You constantly find yourself turning to their old solution, when it really matters, rather than the new way everyone's trying to migrate to. Suggests ways their existing system can handle new business use-cases with only a trivial modification. You keep trying to improve upon their work but keep concluding that there was a good reason for all their decisions.

Depending on the context, someone might be referring to one or the other.

[taneq]

Exactly. There are cowboys and then there are master crafters. Both will rapidly produce awesome results, but the cowboy's results are messy, fragile and temperamental, while the master crafter's results are robust and easy to understand.

[tomaskafka]

This. I understand 10x as a kind of person who creates MapReduce and writes very convenient abstraction around it that anyone can use and become 2x.