I agree 250% with Kai. You could go to the EMC testing lab with an electronics board containing ten ground planes in it shielding every layer from any other and fail immunity and susceptibility testing in the worst way. On the other hand it is possible to make a 2 or 4 layer board, with proper packaging, signal routing, connector selection/placement, chassis design, component placement, and protective componebts in place - etc etc ... and have it pass the first time. Just as Kai has told us time and again....its all about understanding grounding and loop current paths.
MICHAEL