Pruning: The Great Unknown
Volumes have been written about the art of pruning anything but, alas, the information has not seemed to have gotten out to the general public. We homeowners leave it up to the "experts" to take care of the pruning. sadly the majority of the expert pruners are trained by cultural norms and not by actual horticultural practices.
In all fairness to the pruners, part of the problem is that bad choices were made in the beginning of the landscapes' life. Poor decisions were made by the inexperienced landscape designer largely because they didn't know how big the plant would mature to and that there were too many plants planted to begin with.
Nonetheless, the greatest driving force in why plants end up looking like they do is that historically, pruning plants into geometric forms was highly valued. The formal geometric Italian gardens of the Renaissance was a prized possession and a statement either of social status or of political position. So it is not surprising that the pruning culture of today thinks nothing of carving plants into odd shapes. However, 99% of the garden situations are not warranting such treatment but rather an entirely different one that allows the plant to grow and develop into it's natural form. This technique require not only different equipment but also an understanding of what the plants' natural growing habit is.
For example, forsythia loathes to be sheared. It looks so sad when it is pruned this way. forsythia wants to naturally cascade, one branch over the other and grow into a big heap of vegetation. That's why it is important from a design point to place it in an area there is plenty of room to grown out.
More will be written about this topic in the future but if you want to see a great website on the topic, go to WWW.Plantamnesty.com.