Imagine that the sum of the business requirements for a system can be represented by the surface area of a square where the length of the side is 1 meter. Then the surface area is 1 square meter (m2).
Now image also that the shape of the system that can solve those business requirements is a circle and that we have to construct a circle with the surface area of 1 m2. Knowing that the area of a circle is Pi * r^2 then the radius is the square root of 1/Pi which is approximately 0.564 making the diameter 1.128. So we can draw the square and circle as follows:
Notice that when the figures are overlapped one doesn’t cover the other even if they have the same surface area.
So the implementation of the system which can solve the business requirements – but in a slightly different way. To turn the circle into a square custom implementations will have to be done and they are a lot more costly than a standard system.
I don’t have any statistical evidence but in my experience you can usually get 80% of the way with a standard system, but getting to 100% will cost you a lot more.
