There are really important benefits to keeping a mother plant.

Anyone who has grown from seed knows that you always get a certain amount of variation between plants even on very stable ones, you seem to get the plants that just lag behind, or a plant that likes to branch out more.

By keeping a mother plant you grow your seeds out and pick the best genetics to clone from, then you have your mother plant growing and constantly providing clones of exactly the same genetics.

It seriously benefits sog growers, who would like to just "cola grow" have your mother cut the clones, veg for a week then straight into flower.