If I'm understanding your question correctly: on the 5th hole at Royal Melbourne we took the edges of the green down about eight inches from built-up sand splash. (And that's something they have done several times previously.)
We had to work from old topo maps and photos to judge where to stop. With native sand in the bunkers and underneath the green, too, the layer was not obvious to my eye the way it is in other situations.
We have not done the work yet but I know the bunker edge on the 13th at Bel Air will have to come down more than a foot when we get into it in October.