With sire/daughter matings I've done: the calves can stay middle of the herd but you can have a few that will express inbreeding regression such as sterile daughters or off types. What I have created in son/mother has given me more radical change or pushed the calves more to the extreme of the potential than the sire/daughter matings did in one generation. Example: feminine type dam that is exemplary in function bred back to sons: heifers could be extremely feminine (too much) and sons could be unrecognizable as a son of the cow versus a non-inbred son.
So to go back to the basics: what is the reason to inbreed? No reason: don't worry with it. Reason 1: to test a desirable individual to see if their genes are able to withstand inbreeding because you want more of the individual's ability or function? Fine. Reason 2: The individual is "rare" in source, parentage, environmental fit, performance, instincts, ... and you want to maintain that individual's concentrated influence? Fine.
Know that only a minority % will succeed in a true linebreeding program: my guess from historic efforts 15%. Historically in Angus, the peak goodness of a line of cattle will occur long before the line is deemed unnecessary. Many have created good or great and then tried to tweek or improve them to find out that the glory days were behind them.
