Can you briefly run how you care this plant?
Light level, potting mix, winter care, water & fertilizing among anything.

Have you changed anything over the years??
Has this clone always been vigorous??
According to some accounts, the original clone from the French collection was not a easy one to grow, but then I always hate to read hard or difficult without giving reasons why or what makes it difficult.
Original account is obviously way off, or they didn't know what they were doing, or you just have great conditions for this particular plant.
Sign me up for next division, please!!!
I would love to have a fragrant delenatii.