DavidLMO said: ... Some argue no amendments just local soil, but I disagree. But I also do not like to get in religious like peeing contests about it. 
If that trips yer trigger - fine,
As I fill a hole I add less amendments as I get further out.
...
I used to agree with you - amend, amend, always amend! At least for shrubs and small plants. Then I kept reading and "they" always seemed to say that, if you can't amend your whole yard, don't amend for trees.
But I KNOW that I DON'T know.
I would probably preach The Dogma According to Rick if I had a stronger opinion, but all I'm sure of is that I know how to create a mud wallow, and that clay needs planned drainage channels if you go messing up the grade.
The method you describe is exactly what I would do if I had trees to plant, and time and energy to improve a wide patch of soil. Until you said that you disagree, I was cowed by all the people who say "never amend for trees".
