Can a preacher apply the meaning of a text to hundreds of different hearers? Isn’t that the Holy Spirit’s job?

The important thing to consider here is the preacher’s work compared to the Holy Spirit’s work.

• The Preacher’s Work. God calls preachers to herald his word, to report it, to explain it, to give the sense of it (e.g. Neh. 8:8). The preacher helps his hearers understand a text and see how it applies to their lives and their church—how they should repent, confess, obey, worship, and rejoice in God in light of the meaning of a given passage. The fact that there may be hundreds of people listening doesn’t mean that the preacher shouldn’t work to apply the passage. Many points of application will consistently fit a large portion of hearers.
• The Spirit’s Work. God’s Spirit can also give such understanding (and more!), helping people to see how a text is relevant in ways the preacher might not have imagined. More importantly, however, only the Spirit can change the disposition of a person’s heart toward a text and its meaning. Only the Spirit can enable the heart to feel the appropriate spiritual weight of the text. For instance, a preacher preaching on “love of neighbor” can point to the many areas of life where such love must be practiced, but only the Spirit can convict a person of their lack of love and give that person a true desire to love their neighbor.  Only the Holy Spirit can make a sinner willing to receive God’s instruction. Only the Holy Spirit can change the sinner’s desires from opposition to submission, from rebellion to obedience.