I don't know how many of you guys are creative and/or game professionals, but as you gain experience and create, you become faster, more efficient. The more resources you have, the easier your job becomes. You can experiment while still producing at a very high level.
Look at any seasoned artist or designer in any field, you aren't paying them for the time spent on the current project, but the time and experience they've obtained all the way until now. KojiPro team can probably design games in this type of timeframe for the rest of their lives and they'll probably all be very original, and creative. That's just how they roll. It's kind of like how EA and Activision hired devs are able to churn out annual releases, it becomes routine. It's what they know and how they know how to work.