When routing a Gnd line, I wonder if it's best to keep loops open, like so:
or to close the loop, like so:
I could think of some arguments in favor of closing the loop:
PRO Looping arguments:
Coupled magnetic fields try to create current (by inducing voltage). If the loop is open, the current cannot flow. So it's better to close it.
A closed loop offers two paths for the current to go to the Gnd pin. This (approximately) halves the impedance.
But I honestly don't feel that confident about their validity. Can anyone give me more insight in this matter?
I'd also like to know if your answer – either pro or contra closing loops – applies only on the Gnd or also on supply lines.
Note 1: For the sake of this question, let us assume there is no Gnd-plane.
Note 2: The figure above is not a real PCB, only a simple drawing to make the point.