I just answered a question concerning "Salvation" that might be helpful to this question.

With regards to how time passes, the essay begins a few weeks before an important revival meeting at Hughes's aunt's church. The build-up for this revival meeting over the next few weeks happens quickly, over the course of a single paragraph. Then, Hughes spends the rest of this essay describing this single revival meeting, which most likely lasts several hours (at one point Hughes says, "Now it was really getting late. I began to be ashamed of myself, holding everyone up so long.") The fact that most of the essay revolves around a single event in time tells us that this event was an important milestone in Hughes's life.

It's important to note that the essay is written from the point-of-view of Hughes as an almost 13-year-old boy, a child on the brink of adulthood. Thus, while the essay mainly covers a single event lasting just a few hours, Hughes's child speaker ages dramatically in the essay. At the end, Hughes writes, "Now I didn’t believe there was a Jesus any more, since he didn’t come to help me." The essay represents a moment of enlightenment and disillusionment for the speaker. The fact that the essay covers such a short period of time is shows us how monumental this event was in Hughes's life.