In well set up and controlled breeding schemes it is aimed to use the selected sires and dams with the same intensity. In the next generation they get an equal number of offspring. In that way the genetic variation in the population is maintained. All ancestors in the pedigrees of the parents return all in the pedigrees of the animals in the next generation. Such breeding schemes are optimal and sustainable: in future generations all opportunities for selection are still present. In less controlled populations we have a lot of examples of sires that were heavily used in the past in breeds of dairy cattle, horses and dogs. Such excessive use of a few breeding animals has a marked increasing effect of the average additive relationship in the population causing inbreeding problems in future generations. In populations they create genetic bottlenecks.
The excessive use of popular sires often lead to a limited use of other sires or even neglecting sires that were selected for use. That contributes to the effects of genetic bottlenecks.
The first reaction to avoid the excessive use of a few selected animals is to restrict their use: an example is the maximum number of matings that may be performed by a sire. In less controlled breeding programs this often leads to obsession of individual breeders and owners of sires. As a rule of thumb a sire should not produce more than 5 % of the total number of offspring in the next generation.
A positive reaction to the excessive use is to make and propagate a plan in which all selected sires get an equal number of matings. They approach the optimal and sustainable schemes of well controlled breeding programs.