Effective Frequency - Advertising Frequency Theory

Looooong ago Thomas Smith , a London businessman wrote a book called 'Guide to Successful Advertising' in the year 1885! He says it takes at least 20 times for one to be exposed to an ad to make a decision!
Observe at what point the Herbert Krugman's three levels of exposure namely Curiosity, Recognition and Decision are at work !

No one can dispute the power of Frequency... 
However, we need to estimate and carefully judge Reach Vs Frequency and Quality Vs Quantity.
In India, Washing Powder ..... is Nirma.
Thanda Matlab .... Coca-Cola!
What must have made these Brands as generics?
Is it Reach or Frequency or an ideal admixture of both?
Watch the list...
Aspirin is Bayer’s brand of acetylsalicylic acid.
Cellophane is a trademark of Innovia Films Ltd.
Dry ice  is a trademark by the Dry Ice Corporation of America.
Escalator is a Trademark of Otis.
Petrol   is a trade name.
Videotape is a Trade name of Ampex Corporation.
Xerox is a Brand name of a Photocopying machine.