I spoke on Acts 20 recently. A few thoughts:
In verses 1 and 2 Paul traveled around, giving much exhortation to the new believers. He arrived in Greece and spent 3 months there (v3). What do you think he was doing? Could he have been exhorting there too?
Verse 4 lists the associates who traveled with him. We are often told about guys who accompanied him—this was his mode of ministry, just like Jesus. “we were well-pleased to impart to you not only the gospel of God but also our own lives, because you had become very dear to us.” 1 Thessalonians 2:8
Verses 17-38, he called for the elders from Ephesus to meet him in Miletus. He reminded them how he “did not shrink from declaring to you anything that was profitable” (v20) and warned them to “be on guard for yourselves and for all the flock” (v28). Then he continued on his way back to Jerusalem, never seeing them again in this life.