Proper analog set up is something you want to get right. In my experience even the slightest variation from the standard that this tool allows you to hone in on, has a negative effect on sound quality. The Dr's tool just allows you to get "perfection" easier than any of the others I've used. It is expensive though.
Dr. Feickert Protractor
What will Dr. Feickert's protractor do that the paper alignment protractor that came with the turntable can't do?