This shouldnt be the case though, there has to be processes that can be automated or streamlined to shorten this process. How is insomniac able to put out a new triple a game every 1-2 years?
Insomniac had way more workers than ND, in two separated offices. They always have been working in 3 or 4 games at the same time. So on average they release a game per year or more. ND were way less people and prefered to work only in a big project at the same time.
Jimbo and Hermen decided to highly grow the manpower in all their internal development studios a year or two ago and they continue growing. Their idea was to export the Insomniac workflow to at least their other big studios. So it's soon now because to build a team and make an AAA game takes time, but I think somewhere in the future each big Sony studio will be releasing a game every year or two.