We emphasize something we want others to pay attention to because we think is important. We raise our voice, lower our voice, or talk slower. We raise our eyebrows, maintain eye contact, or use gestures. If the message is written, we might use boldface, or italics, underlining, the dreaded ALL CAPS, or even worse, ALL OF THEM TOGETHER WITH MULTIPLE EXPLANATION POINTS!!!
There are more nuanced ways as well. You can return to an important point, feature it on a list, or spend more time talking about it than anything else. This last technique is used by the writers of the gospels in at least two important ways.
First, their accounts of Jesus are not nicely divided into 33 even segments (one for each year of Jesus’ life). They are heavily weighted toward His three years of ministry which began at age 30 (Luke 3:23). But they don’t stop there. Roughly one-third of their writings are about the last week of Jesus life. In Mark for example, he begins the last week of Jesus’ life in chapter 11—that means that 6 of Mark’s 16 chapters cover the final week of Jesus’ life. So, the gospels are primarily concerned with Jesus’ ministry with a heavy emphasis on His final week.
What does that mean?
To begin with, it doesn’t mean that the rest of Jesus’ life was unimportant—it means it just wasn’t quite as important (especially from a salvific perspective) as His final three years. The same thing is true about the last week of Jesus’ life—it was of the greatest importance—the fulfillment of His mission, the climax of His ministry.
These things are true whether you are reading Matthew, Mark, Luke, or John and are helpful to keep in mind. They prevent us from turning Jesus into simply a wise teacher, a benevolent activist, or a social reformer. They help us to keep the emphasis where the writers placed it.