I have used the 3000 grit, but if you don't do every step perfect, they don't work at all.
You can still end up with previous scratches.
I like starting with 800 grit (3M purple paper), then 1000 grit dry, 1000 grit wet DA, then a quick 1500 wetsand.
Then I use a white wool pad to start with.
It's a weird system but I have it so I can do it quickly and efficient. I have it down packed.
I can normally have a car ready to buff in about 2.5-3 hours.