Axactly mate .If a lad buys /is given a pup from previously proven lines and the dog/bitch dont make the grade ,then ive known some to breed off it because the blood is right ,hoping to get one next time .Ive known lads to waste years on a breeding because the root stock was good .No,its time to cull when a terrier dont have the work in it .Different when they have several seasons of graft under the belt ,then decide enough is enough,you can judge it by those years and decide whether it was good or not .
Most of us cant impress enough on anybody not sure about the game that WORKER TO WORKER I