Sometimes it's good
I did my belt change from the information in the 107 manual. I have found that the manual is most helpful to an experienced mechanic. Everything isn't spelled out and I wouldn't call them excellent but it has helped me a lot and saved me thousands.
1985 Mercedes 500SL Euro (Gray market)
1995 BMW 520i Euro (Gray market)
1992 BMW 525it Wagon
1994 Honda Del Sol Si