Why should a person who trims trees for a living know about the effect of apical dominance on the shape of trees?

Apical dominance is an important trait for trees that must be carefully taken into consideration when trimming. Each tree has different apical dominance, one must be familiar to this trait to manipulate and achieve the desired topiary or dwarf tree.  Apical dominance has an impact on foliage growth, branching, and branch strength of the tree.