I believe in this case they aren't waiting for it to mature. They use what's called LVL (laminate veneer lumber) which is basically thin sheets of the wood glue

I believe in this case they aren't waiting for it to mature. They use what's called LVL (laminate veneer lumber) which is basically thin sheets of the wood glued together (think plywood but thicker) and then recut into dimensional sizes. The end product is both stronger and straighter than conventional lumber. And because you don't need a large cross section (almost literally any size will do), you can have a pretty short planting -> harvesting cycle.