Once a plant is deep into flower it is too late to clone it, so the standout pheno from a pack gets smoked and lost unless cuttings were taken in veg. Snipping a few lower branches from every plant a week before the flip and labelling them costs nothing, and the ones from ordinary plants get binned. The cloning walkthrough on https://potentthcseeds.com was written with pheno hunts from THC seeds in mind and stresses this timing more than most guides. That is how a good grow becomes a keeper.