While working, I use only water in the pad cleaner so that I can clean pads without introducing degreasers in the pads and in the water. I can usually get pads 80-100% clean with just water when the product is still wet on the pad. Some products are very hard or almost impossible to remove completelly with this method: Cleaner waxes and sealants. For exemple, when I use D166 and the pad gets dirty, after cleaning it with only water I get a pad that still has a lot of products in it but dirt and paint residues are gone. So for me, that is good enough to use it again on the next cycle (I use a 2 pad system, use a pad for a panel or two, clean it, then switch to the other pad then repeat).
When I want to clean the pads completelly, I let them soak in McKee's pad rejuvenator solution for about an hour then put them in the pad cleaner again with only water. A single cleaning is usually enough.
A trick for the pad cleaner: Use a rotary with an extension nut to clean the pads. It's much more effective and easier than using a DA. Also the pads come out dryer after spinning them at 3000 RPM in the pad cleaner.