I grow Walla Walla sweets and only pull them when I'm ready to eat them. What stays in the ground will grow new green tops in the Fall (the old green tops will die). We then eat the green tops at that time through Fall and Winter. Come Spring, I let them grow new tops. These new tops will grow seed heads. The seed heads will bring in Bumble bees which is a good thing (especially around here). The seeds will then be used another year.
Keep rotating your garden like this and don't rely on the local store to have seeds each year. There will come a time when they are not available and if you have extra seeds that can reproduce, they will be worth a small fortune.
Wisdom is worth a lot.
I love garden talk. I've been doing gardens since I was 8 or 9 years old.