Transit branches live differently from settled ones. They are rebuilt more often, routed through more varied conditions, and asked to preserve identity across repeated physical reconfiguration. Under those circumstances, route cycles become a better measure of age than ordinary elapsed time.
A transit branch may consider itself experienced not because it has existed for a long number of years, but because it has survived a certain number of high-stress passages while preserving coherence. Wear, repair, and route memory matter more than birthdays do.
This makes transit populations unusually difficult for settled colonies to classify. They can be materially young and historically dense at the same time. That combination is part of what gives them their reputation for practical patience and odd social distance.