What is the monkey’s paw

According to the website "The Monkey's Paw"  is a supernatural short story by author W. W. Jacobs, first published in England in the collection The Lady of the Barge in 1902. In the story, three wishes are granted to the owner of The Monkey's Paw, but the wishes come with an enormous price for interfering with fate.

Explanation:

faulty parallelism is a construction in which two or more parts of a sentence are equivalent in meaning but not grammatically similar in form.

the correct version of this faulty parallelism in the sentence is:

the hikers knew that the hike was six miles, that it usually required the entire day, and it would not be wise to start after 10: 00 a.m.

the problem is the last sentence, the first two have a basic subject+verb+object structure.

so, to give a proper balance to the structure, or better said, to give a parallel structure, we must write a basic s+v+o structure in all three sentences:

the hikers knew that the hike was six miles, that it usually required the entire day, and it would not be wise to start after 10: 00 a.m.