You must take in mind the diference at reference point, and current flow path.
There is no problem to you interconnect all that ground nodes.
Moreover, it is mandatory to be refered on same point.
However, the concept of different planes, consists to isolate as much as possible the ground planes into definite geometric regions, but electrically connected. The reason to do that, is to minimize effect of current flowing at sensitive circuitry, wich can drop different voltages at different ground points.
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