There are many standards for writing the "perfect" story, but every person sees and values it differently.
For some, the perfect story ends with man and maiden riding off together into the sunset, happily ever after.
For others, it's the Romeo and Juliet approach, the undying love that ends up dead.
Still others kill one lover but not the other, leaving a languishing lover in the lurch.
If "perfect" is in the eyes of the beholder, there are as many perfect stories as there are people writing them. However, many people pick one style and stick to it, however feeble and weak it becomes from use. George Orwell, in an essay entitled Why I Write, from 1946, said,
A lot of what we do could be defined as upkeep. We've reached a certain level of ability, and now we're working to make sure we don't decline. It's like this with a lot of things we're used to doing every day: driving, cooking, walking down the steps, conversational habits.
There are many artists who use this style in their art as well. The good painter already knows a style that works for him, so that's what he does. The good pianist likes Chopin, so that's who she plays. The good mathematician knows the answer to this type of equation, so that's what he works on.
Therein lies the distinction between the good and the great, for the great artist tries what he has never tried before, the great pianist plays who she is not used to, the great mathematician works to tackle the unsolvable problem.
And the great writer always tries something new.
Once you've perfected something, practice it and keep the skill—but don't camp on it. That's not how you become great.