Only three missionary journeys?
Flip to the back of your Bible and you'll find maps outlining Paul's "Three Missionary Journeys".
We all use the phrase. Unfortunately it's misleading. Paul had ten year's missionary experience before he set off from Antioch on his "First" journey with Barnabas in Acts 13 — Damascus, Arabia, Jerusalem and his home region of Cilicia and Tarsus, the city in which he was born.
There's good evidence he was released after his first trial in Rome and went on to Spain and Crete before his final arrest and execution under Nero.
Luke knows a lot more than he tells us.
Have a look at the list, fifteen locations. He wasn't just church planting in each place. Whole regions were touched by the gospel. He completed his work, and moved on.
So, which church leaders today are operating with a similar job description to Paul's? Who is taking responsibility for pioneer evangelism and church multiplication across whole cities and regions? By responsibility I don't mean an organisational title, a mean someone who is taking responsibility, leading by example, and making it happen.
If local churches were doing their job, we would still need the equivalent of Paul and his coworkers today.