I'll try to describe how Si works in my everyday life.
It's like... there's a bullet point list for everything. When I thought about composing this post, my mind "scrolled down" on my list of ways to describe Si to get to my current best way to describe it. I like to call them "units of thought". I narrow things down to these units. You may notice that I often speak in a rather sequential way; this is me going through my unit of thought.