Speed run through DVD with ddrescue

I'm using ddrescue to get data from damaged DVDs. If DVDs are badly damaged, the CDROM drive really struggles to read at all, and can spend 10 seconds continuously readjusting the beam arm or whatever it's doing. So to avoid pointless strain on the drive, I thought: 1. Set a high block size value. 2. If any errors are detected, don't try to reading again; just skip ahead until readable data is found. However, the options in ddrescue have got me confused. What's the difference between --max-errors and --retry-passes, and what are the contributions of --no-scrape and --no-trim? Ultimately: 1. What are the correct options to rush efficiently through a DVD once as quickly as possible? 2. Since ddrescue can be run multiple times filling in the blanks on an existing file image, what would be the options for a second, more thorough run?