A picture is worth a thousand words, so try this:
The attached photos are of a multiplier board out of an old, long dead, 166Mhz (??) transmitter/receiver.
Look at the component side, the large areas of tinned copper are a "ground plane". You will see that there are some areas where there are islands in the groundplane for component connections, but most of the connections are made on the "wiring side" of the board.
Using a groundplane like this gives a common point with low inductance between different areas of the board. minimising stray coupling between stages.
When the board was in use, the coils had screening cans around them, and the screening cans were soldered to the groundplane.
JimB