The lube pad needs just a few drops of lube over its surface, smoothed out with your finger, to where the surface is moist.

The area can be small or large, depending on your needs.
It is also nice to keep the pad clean from powder flakes, tumbling material and other materials.

You can always add more if the cases use up the lube.
I never had to wipe out my dies if the pad is prepared correctly.