If people could not find a pattern, then an individual thing in a bigger picture does not make sense. Coherence is everything in developing a brand, and a very essential one at that.
First on the list is character. When one plays music, any type of genre could be used in an album if the musician has a signature voice or instrumental style. People who recognise and are highly interested by this style would definitely be interested to see how this particular style works with different genres. This style or character becomes the artists’ selling point, at least one of them.
Next is fashion. Musicians, especially idealistic and independent musicians, often want to make music and not be famous for their looks. However, coherence and appearance is everything. Looks will always play first before the music.
During the 40s and 50s, radio became the means of mass media. This allowed people to appreciate music rather than the appearance of the musician. But in today’s visually-fuelled era, one must adjust. It may have played down the musical-technicality department, but to build a brand, this is essential.
Lastly, coherence comes in the form of a band logo and idea set in an album. If an album is discussing about love, then by all means, it must discuss emotions in a single song. It may talk about different things, but it is important to retain the form of expression in the form of prose and words the musician uses throughout his or her song.