Oh boy, this sure does seem complicated! you'd think after practicing mindfulness for about 3 months now, I'd know a little bit more about it!
I like your analogy Perna... an assembly line. Another one that I often use is like picturing slides on a movie screen. One comes, you observe it, and then it leaves and another one shows up!
Only my problems is I think i'm already thinking too much about what was on the previous slide, that i can't focus on the one in front of me, and i just keep falling further behind.
If only we could just "observe" things without getting all emotionally involved all the time!