I interpret it as "Sanchin is in everything" everything Uechi, that is!
Here's what I mean.
As one progresses through the various "new" techniques, learned as we go along our Uechi path, we start to think, "gee, there seems to be a lot of NEW things to learn!"
But if you apply the principles of Sanchin to these supposedly "new" principles or techniques or moves, you see that Sanchin principles are actually CONTAINED WITHIN, and EXPRESSED BY these supposedly "new" techniques.
Instead of having a thousand tools for a thousand individual jobs, you have three tools which can perform a thousand jobs: A saw, a hammer and a lever.
(I'm not relating these specific tools to Sanchin!)
But, you find certain CONCEPTS and PRINCIPLES expressed in the applications and the techniques, over and over, and lo and behold, Sanchin is the template or the "try-square" for all these concepts and principles.
HOW MANY OTHER Karate "styles" base their ENTIRE CONCEPT upon their FIRST, MOST FUNDAMENTAL Kata?
I know you emphasize the mental/spiritual aspects of Sanchin, but my examples address the physical ones.
Hey, I'm a guy!
But seriously, I think of it as "Sanchin is in all", NOT "All is in Sanchin"
I have a question (challenge!) for you...
What is YOUR interpretation of what Sanchin means for YOU?
Can you answer this question in PHYSICAL terms?