If the Lapita culture followed a slow boat model, then eventually it would stop migrating early on. It's more likely that the Lapita culture followed a fast boat model. That's not to say that they didn't stop at some areas and settle for a while or even settle permanently (only a part of their group would settle permanently), but a portion of the group or the next generation would go on to find new islands or coastal areas to settle. The Lapita culture, unlike other cultures that were in Island Southeast Asia and Near Oceania at the time, were a true maritime culture, and it allowed them to just continue on migrating generation after generation, partly because there were no competitors (no one like them at the time) to hinder their progress. In more recent times, the Bugis people of Indonesia had experienced a great migration because they were able to exploit resources that other Indonesian groups weren't simply exploiting. I don't know too much about the Bugis people so I can't elaborate more.
Look at the Turkic groups of Central Asia. They were a very mobile group. Although they settled at times, it's their mobility as a group that allowed them to continue migrating westward and in other directions. Turkic groups and the Mongols (and Huns if Huns aren't considered Turkic) also developed a mobile warfare culture that the world had not seen (at least at their scale) until then which made them successfully migrate westward and in other directions.