I do not understand the need for a definitive path, given to the fluid when it has already passed through the flashpoint. In my mind, such a path only adds volume to the block, but does not add value to it, from a cooling point. I can agree with the inlet being on top of the core, but only in Cathar's case of design, where a jet, induces a much higher velocity and from that the turbulence induced, multiplies the effective surface area.
for the noob, trying to rap his mind around all this, think of it like so. There is a bunch of constants involved, and then there's a couple of things, that one might call multipliers....
for instance:
the total effective surface area of any give design, is a constant.
So is the actual volume of said design.
The aerodynamic characteristic, or should I say fluidynamic....

of the flow path is a constant to, a very important one.
Now obviously the flow rate is a variable, that depends on a bunch of other things, external to the block.
flow rate should never ever depend on the block's design. The block is not there to make the system flow properly. That is where so many go astray, because as soon as you start optimizing block internals, to make the pumps life easy, you loose cooling performance by the gigawatthours and a half.....
turbulence, I like to think of as a multiplier. It apparently seems to multiply the effective surface of the block. I'm saying apparently, because we all know it does not really do that, even though the amount of cool water getting in close proximity to the copper, is greatly increased by it.
So how does all of this go together
In my mind, the ideal is to be able to get every single water molecule, to touch the surface of the internals of the block, and immediately after doing so, be evacuated
with as little interference as possible to the incoming molecules.
Believe me, that's a tough one.
You want to have as much surface for as little volume. The smaller the volume, the faster it can be replaced with fresh cold fluid. The bigger the surface, obviously, the more fluid molecules will touch it at any point in time. for this surface to volume thing, one needs to get into Mathematical shapes and the relation between there volume and surface area.
this... might give one an idea of what it's about.
Some of the laws involved are mentioned
here