I have one Rosemary bush that is over six feet across. We use as much as needed, and give away limbs of it to neighbors. Just take a limb, stick it in dirt and it will grow.
My big plant came from one single stalk that was less than a foot long. I’ve given neighbors potted plants that are growing like weeds.
I planted 3 tiny pots of rosemary around the deck to my garden shed. They are huge. They are beautiful. Now I need to start sharing some.