Lots of trial and error went into breeding the dogs they did until they got it lined out. Just like every one else they had pairings that didn't work but nobody knew because they were dealt with at home.
Boy you said it right there. This is how a person becomes a great breeder of great dogs trail and error hands on experience and time, time, time there is no substitute knowing what works and what does not .
I would like to say to the people that do not believe this . Do you think in the 1800's and early 1900's any of the old hound breeders had any knowledge of genetics the big words, geno this and geno that, homo this and homo that LOL , what about the ole time Pit Bull breeders Joe Corvino , Gaboon Trahan , Mr Wallace, Mr Hinzel, Earl Tudor , Bert Clouse and the list goes on and on . No I don't think they did it was trail and error and they developed their breedings skills by using their dogs and they developed their eye for great dogs and they bred them by instints being line bred inbred and even outcrossed.