Best Answer Paul Newton, 21 May 2014 - 06:08 AM
You would not need to do it for the logic speed, but consider whether those grounds are carrying power between the boards.
If they are, you may still need a few grounds (rather than just one) to ensure they provide a low resistance path between the boards. The fewer grounds the higher the resistance, the hotter they could get, and there would be a voltage differential between the boards which could confuse the logic gates.
Paul
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