This is something I learned in my over 17 years in marketing and copywriting.
It’s also something that Tony Robbins talks about when he refers to the six-code needs of every person. Two of these needs are certainty (or predictability) and uncertainty (or variety). Finding a mix between the two makes every marketing effort more effective.
And the same goes for every artwork you produce.
Some elements must be predictable.
When a person reads a fantasy novel, he expects to find certain canonical elements.
It can be multiple races, castles, swords, dragons or magic. But there must be some of these elements; otherwise, the average reader will feel like he is not reading a fantasy novel. And, consequently, he will feel cheated out of his time and will not appreciate the book. The same applies to every form of art and it’s a must if you want people to get into it.
Of course, too much predictability makes your artwork like every other artwork of the same genre out there.
Some elements must be unpredictable.
There’s this myth nowadays that everything must be 100% original.
The truth is that there’s no such thing as originality. There’s just the ability to mix different ideas and principles to make something completely new and different from what we are used to. That’s why we see fantasy mixed with sci-fi in settings like SpellJammer for Dungeons and Dragons. But of course, too much unpredictability makes things too complex and unaccessible for most people.
This is why it’s always important to mix things that are certain and tried and true with things that are uncertain and spice things up.