Every one should know what their soil base line is when they begin gardening, farming or just putting in a lawn.
If you don't know what you have to start with, how do you expect to fill in the blanks so you are growing great soil?
I have posted up the what and how of soil testing soil testing
and I do think that it should be done, especially when you first get on a piece of land.
I also like to test in the fall of every year, just the garden beds (I treat the whole of my acreage and base the amending on what the garden beds tell me is needed).