It is a peculiarity of marketing that to work well, in most cases, a LOT of different things have to be done right.
It is characteristic of great artists that they take great pains with fine details of their work. The same is true of the commercial art in marketing but it is true of all the other, non-artistic aspects of a marketing effort.
A great ad, for example, may be a complete wow artistically. But is it being run in the right publication? In the right location? Is the headline well-chosen?
One word changed in a headline can make a difference of 40% or more in the response an ad produces.
The Devil is in the Details. Genius is 98% Perspiration and 2% Inspiration. Two hackneyed sayings that are very, very true in marketing.