I tag all my tracks from the same album with the same cover artwork.
So it depends on which album I own from this three:
The only exception are compilations like "UK Top 40".
On such compilations every track has its own (mostly Single) cover artwork.
But to be honest:
I don't search for them. If they are there already embedded: Fine.
If not, I set the same "UK Top 40-Collection" cover art work to all the 40 tracks at once.