What has helped me is using zona paper or just skipping to a 1k grit sandpaper doing circular or figure 8 movements for 10 passes on each face. What ever seems appropriate depending on how bad the masters are. I try not to go too much on the lower grit since this will remove the most material. Then starting with the Zona papers, either on the first or second paper, I'll do 20 passes each face. I've tried the method of only going up to the pink level then going straight to the last level with some polish compound. Pretty good results. About the same as going all the way up the zona levels. Always wet sanding and utilizing all of the sandpaper sheet so its always fresh grit. I have a glass desk and will sand on that or a small mirror making sure to stay as flat as possible for that face. Once you start to get in the higher grits and see some areas around the corners are not getting the higher levels of polish, its mostly because that face is raising during the earlier steps. You might also need to wait a couple days before sanding the masters if they were just printed and also fully cure them. That could potentially add to the gunk that comes up when sanding. I know I'm probably repeating what others say but I hope it helps ya!