Dave wrote:
"The more and longer the better of course!"

Increases cost and wind loading.

If the ground plane is high above the earth, it isn`t required to hide
the earth from the radiator to prevent displacement current flow loss in
the earth.

If I recall the story, George Brown, the inventor of the ground plane
antenna wanted to use only two opposing 1/4-wave radials in his antenna,
but was persuaded by the RCA marketing department to use four.

The extent of the ground plane affects the radiation pattern. See Figure
21-10 on page 720 of the 3rd edition of "Antennas" by Kraus.

The imnfinite ground plane (soild line) has its maximum radiation at
zero-degrees or toward the horizon. !/2-wave radials (dotted line)
produces a slight elevation above the horizontal, but there`s not much
difference in field strength at the angle if the ground plane is
infinite or has 1/2-wave radials.

If you were a medium wave broadcaster, you would want the infinite
ground plane. Brown, Lewis and Epstein at RCA determined the number of
ground radials needed for very high efficiency long ago.

Best regards, Richard Harrison, KB5WZI