This is all true, but friction does take its toll on velocity. Friction in a "Y". More pipe surface, more friction. You can subdivide and subdivide, but at some point all those little pipes will be passing less water than tear membranes.*
You can get a better handle on this, zee bee, by figuring what the pressure is at a given section, and then how that pressure causes flow.
*
Valentine's Day and wife is out of town.