Why do we spend so much time on Naihanchi?

We spend a lot of time practicing Naihanchi.  We practice it slowly, fast, and with power.  We break it down and work on its component parts. We analyze the movements for self-defense techniques and applications. We try it at different speeds. Why so much Naihanchi?

It's because there's a little Naihanchi in every kata!

Every time we step from one technique to the next in any kata, we're doing Naihanchi. It doesn't matter if we're practicing the most "basic" Fukyugata Ichi or the most "advanced" Kusanku.  Every time we take a step, we're doing Naihanchi. In Kishaba Juku, Naihanchi is our foundational kata; our root.  If we do good Naihanchi, then all the other kata will also become good.