Plinth mass vs. Foundation mass

In pursuing my analog education, I perused an old thread
on here, a long thread, about Panzerholz plinths.

This thread, along with numerous others, got me to
formulate the following question:

In the general attempt to isolate the platter & cartridge
from vibrations in the rest of the universe, where is the
added mass more/most effective, in the plinth or in the
mounting base ?

I suppose a 100-lb wood plinth sitting upon a 500-lb stone
table would be fairly effective. But what might be a more
"compact" solution ? Is it too subjective to ask where
is the point of diminishing returns ?

Thank you in advance for insights & ruminations.