In the first example, "the" is not needed the second time. This is because first and second are adjectives modifying a common plural noun (paragraphs).
The first and second paragraphs are extremely long.
However, in the last example in the question, all the articles are needed since we are talking about separate coordinate nouns.
What are the situation, the task, and the result of your story?
We would not need an article for each of the nouns when the separate nouns combine to form one single idea. A common example is:
- The officer and gentleman escorted the lady to the car.
- The officer and the gentleman escorted the lady to the car.
The second sentence would mean that there were two persons escorting the lady to the car, while the first one just has one person (who is an officer and a gentleman) as the subject.
The use of "the" can also be important while using adjectives with non-count nouns. Another common example is:
- I would like to buy the red, blue and yellow cloth.
- I would like to buy the red, the blue, and the yellow cloth.
Since cloth cannot be used in the plural, it is the definite article the that tells us whether I would like to buy cloth that is red, blue and yellow, or three separate pieces of cloth (one red, one blue and one yellow).