Insomniac has two studios, one in Burbank, another is in Raleigh. It also does multiple projects at once in the Burbank so no, they are not delivering two console games a year. In fact, since 1996 they've done it only in 4 years (with the second game being a R&C game, which is more of a game design than a programming project) just as many years as they have not released a single game. Each of their big games is 2 years+, just like any other AAA studio. They start pre-production on the next project in the middle of the current one, just like any other AAA studio. 6-8 months in the console games nowadays is either a port (porting a game from one platform to another) or some horrible shovelware you find in the happy meals. In 6th generation a AAA game could be 12-18 months and if you worked really hard you could do something like Rogue Leader in 9. But 6 months is something from the 8 bit era, before Insomniac's times.

Sorry, I tend not to read hn in places I can watch a video. Maybe I'll remember to check it later.