The sketches show a parallel system with supply on one side and return from the opposite side. The flow path from supply through any one branch to return is exactly equal to the flow path through any other branch. The system will self balance, even if the flow velocity through the branches (I'm too lazy to do the calculation) is laminar.
I expect possible trouble from two sources.
The water velocity may be too low to push trapped air out of the branches. Then you will have unbalanced flow.
The pressure drop will be extremely low in the branches. If there is any elevation differences, temperature / gravity effects need to be considered.
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