Removal of some or most soil from about the roots may be quite helpful for small trees in containers, and perhaps for small transplant trees with roots wrapped in burlap etc, but for larger trees becomes more problematical the larger the tree: eg, tree transplanting equipment, which lifts the tree & roots & soil: when planting, something is required for support, and newly placed noncompressed soil is great for small and new root growth, but structurally less supportive of weight. The larger the tree the more problematical structural support and possible affect on root surfaces becomes. And different types of trees have different types of root systems.
Generally, except for small specialised type trees grown in containers, leaving soil that is sort of attached tends to keep small roots intact; and small container tree roots are very very carefully separated and the tree very very carefully set into a new container(or maybe the same container), the container soil intended to be replaced to provide fresh nutrient. Seedling roots are fragile, but so are the small & tiny roots of large trees.
Similarly, when transplanting/ planting, it's typically recomended to gently fluff out the roots & unwind etc circled roots. In that process loose soil tends to fall away, but pulling at the soil, especially if it isn't moist, also pulls at the roots & can be too much for little roots.
One mild guide is to consider the relative size eg of a burlap wrapped root ball to the size & age of the tree: some are quite little compared to the size eg of a 1.2 m citrus, and that situatuation would tend be different from a 1.2 m citrus with a burlap wrapped ball six times the volume re the extent of root crowding present & how much soil might be loose. Gently disentangling/ separating circled roots etc is typically associated with some soil falling away. Also, some trees are more sensitive to replanting than others, and age matters too. Time for establishment of root systems is to be expected, and could be longer than 4 weeks.
