Nope. Final Fantasy XIII I think was originally intended for the PS2, but then they changed their mind, and moved it onto the PS3. They then created the White Engine to be the Graphics Engine for the next-gen consoles.
I know that Insomniac have to create new levels, but creating new levels is a lot easier than creating a completely new world, with completely new characters, and design a completely new battle system. Nor does it have to create a plot with the level of detail that Final Fantasy does. And it doesn't have to create the amount of NPCs that XIII does.
Put it this way - it takes me, on average, 60 hours to play through a Final Fantasy game. It takes me about 10-12 hours to play through a Ratchet & Clank game.
I'm not knocking the Ratchet & Clank series, or Insomniac, I'm just saying that it is a lot harder to make a new game (which is basically what each new Final Fantasy is) than a sequel. Especially when that game requires strong characters and a strong story. And thus, it is a bit unfair to compare Insomniac's development cycle with any Final Fantasy development cycle.