But maybe if the amendments are tapered off gradually, roots will make the transition from the improved soil to the unimproved clay.
It probably depends on the tree, the clay, the site and the gardener. But I would trust people with "tree experience" more than me.
I no longer give a lot of weight to "Internet consensus" about gardening matters. I think a lot of "Internet experts" are mostly expert at quoting each other in slightly different words, not necessarily thinking about what they're copying.
