It probably depends on the company and project. If it's a hugely ambitious one with tons of challenging tasks to work on, then everyone being '10x times better'

It probably depends on the company and project. If it's a hugely ambitious one with tons of challenging tasks to work on, then everyone being '10x times better' would mean it'd speed along and get done in about a quarter of the time. For most projects/companies? I suspect you probably couldn't get much more efficient if everyone was significantly more skilled, and quickly realise how little meaningful work there is to do there. Given 10 super expert programmers the task of creating another CRUD app or client website and I suspect at least 9 of them would probably quit by the end of the month out of boredom.