Low-hanging fruit is the corporate metaphor for easy wins: improvements worth having that take little effort to get, picked first the way you would pick the fruit you can reach without a ladder. In workplace projects it usually means changes like auto-releasing no-show bookings or fixing the visitor queue, done before anything structural.
The phrase earns its cliché status through overuse, but the underlying discipline is sound: sequence work by effort against impact, and bank the quick wins early to fund patience for the slow ones. Just check occasionally that the tree has anything left below head height.