Si is much more abstract than is typically portrayed. It has NOTHING to do with washing hands, doing laundry, cleaning, etc. Remember that functions are about HOW you do things and not WHAT you do.
I'll describe my experience with Si as a type where Si is quite pronounced.
Si for me is about flow, and what fits into my flow and what doesn't. If you look at Si in terms of the information elements, you have Si = external field dynamics. What this means is that someone like me is gonna be really into being in harmony with my environment (the external field around me) (Ni is an internal field, so Ni types will want to get in harmony with the internal field around them).
For example, as I'm going through my day, it all seems to have a flow, an abstract essence that characterizes the day or given time period, and as I experience each moment, and think about what to do next, or what is coming next in the day, I will know very keenly what fits into my "essence" of the day.
Another example is that certain places seem to have music that fits perfectly with them. Since I was very young, I would always think of certain places that would go with certain songs. I mean even when I first heard Kenny G's trademark song "Songbird" when I was young, (and I DO listen to more sophisticated music than Kenny G
but I've always liked a few songs of his lol) it made me think of the New York City skyline from a very generalized far away perspective, like I can't quite describe this, cause I had always associated New York City with being sophisticate, shining with bright lights, and a very smooth overall feel it gave me, like there was plenty to explore, and when I first heard that song, it was much different than typical songs I heard on the radio, this one seemed a bit more dreamy, reflective, etc. I may sound like I'm freely associating here, but its hard for me to explain that specific example.
Sort of like this kind of a scene:
Or even something like this, where there is this brilliance and color of the lights, like the bright tone of his saxophone across a very smooth harmonic background like that, in the way that the scene comes together harmoniously for me.
Again, you may not get the same out of it that I did, but that's part of the point. An aspect of Si is also fairly personal, since the idea of Si is becoming one with the field, or in harmony with the field. The field with Si being external.The reason I got what I got out of that song is because it fit into MY flow, into some feeling that had context for me.
This may sound incoherent, but this is how I sorta think in a given minute with Si: "I'm here, computer in front of me, air conditioner blowing, 6:48, getting late, see sun starting to go down, I should get out of what I slept in, where am I gonna be tomorrow, how's that gonna blend, (I see how I will transition from this state of mind into where I'm going to be tomorrow and what I'm going to be doing), I had a late breakfast/lunch, where, what will I eat and when so it'll feel just right at just the right point to make my day/night seem smooth." (Basically all of these awarenesses revolve around a core essence that Si seeks to make everything fall in harmony with).
Also if I just reached a new level with person that gets worked into my Si "Oh yeah, I'm like THAT now with them, I'm living now with a new level of relationship. I have that added color in my life flow".
Oh I wanted to add, and I haven't figured out if this is Si related or Fe related for me (prolly Si), but to me looking at the towers of different bridges, each bridge seems to give off a different "face" in terms of the design, and a different personality, and even the angle that I look at it gives off a different personal feel to me.
For example, with this particular bridge, looking at it straight on gives me a certain feel:
While looking at it from another angle gives me a different feel:
And actually I just realized, I would have preferences to want to take certain bridges over others even if it made no difference travel wise, because certain bridges had a certain feel associated with them for me, and I'd like it better than others. Actually when I was really young I'd go so far as to say that if my family ended up taking the adjacent bridge to the one I really liked, I felt that I was missing out, as I could see the other bridge from the adjacent one, and I sorta got the feeling that I was "missing out on the party". I know this sounds ridiculous, but I think this is kinda how Si works. Si can be VERY personal, and as you can see, it can be very abstract - I can attach contextual meaning to things that are clearly not there if looked upon through an objective lens.
And if you're curious how Ne works for me, I used it to come up with that phrase just now "missing out on the party" cause ultimately, Ne can search through Si or whatever contexts for matches in concepts. In this case the concept was "feeling like I'm missing the experience of the other bridge", so I took the concept of "feeling like I'm missing out on something good", and used Ne to search for a match of something in another life situation that yielded a similar feeling. "feeling like I'm missing the experience of the other bridge" is one object, and "missing out on the party" is another object. Ne = internal object statics - ie draw connections between the internal object statics. See how it works?
I hope this helps, even tho it may seem abstract.