When it comes to planting trees and shrubs, there is a tendency for a couple of things to happen.
Firstly, with such a huge choice of plant species available to buy, there is often a tendency for people to buy plants without truly knowing either what they are, or what their cultural needs are.
Secondly therefore, because of the desire to see a space in their borders filled with something, most people tend to plant too many individuals in a group planting together, without taking into account the potential ultimate size of each plant. This looks fine for two or three years, but often this leaves those plants growing much too closely together with the resulting loss of form and habit. And this happens because now there is an element of competition between them. Competition for light, moisture and nutrients.
I have seen examples of that kind of approach on professionally produced plans, where a Landscape Architect has put 65 plants of one species in a block planting where 3 would have filled the space in 3 years. OK, it looks alright for 2 years, but after that it becomes a very unattractive jungle where many weaker individuals will start to die off. The plants are then so close together that it becomes difficult to control weed growth effectively – altogether an unsatisfactory result which, rather than being an attractive eye-catching display, ends up being an eyesore instead, and an expensive waste of money and also of time.
After all, it is definitely more satisfying and more economical to get it right the first time. Sometimes, less is more.