I am not moving and I am correct.....but only twice a day.

I may, or may not exist on a material plane, but I am the one who divides the space, and The one who stops everyone from moving forward. What am I?

Do this down, when there’s too many to choose. A few choices, win, win. Weed out choices, lose, lose. Your path will condense, sides will tighten, get smaller. Minus first: Silent ammo, used when wrist is near collar.

I'm highly determined and persistent, but if I'm split into three, I become meager distribution to a large community. My first three are two more than my length. My last four a bustling place to live, but not for everyone. I can be used to describe D.

One twelfth of measure, Geometer's Worm Add 'P' before me, An uncomfortable squeeze to make you squirm.