Mulch, mulch everywhere - but not a bit to spare

Everywhere you look mulched tree rings vary. We see huge mounds that look like volcanoes to smooth surfaces barely flush with the sod. What is best? ... A tree benefits most from a mulch ring with at least a 3 foot radius giving it space to absorb water without competing with the sod. Ideally the mulch ring would expand along with the drip line of the tree.  In that circle there should exist a 3 inch depth layer of mulch that slowly slopes at the edge of the tree ring, then again near the crown of the tree where the trunk flares out.  That layer of decomposing mulch should be periodically cleaned out.  As the mulch decomposes into soil matter it requires more top dressing of mulch but also increases the height of the soil causing the surface roots of the tree to move further upward to feed. Keep the soil low - the tree ring slowly expanding with the growth of the tree - the mulch slightly sloped and at an average depth of 3 inches for best results.