My last mansion space clearing project was such a big job — we did it with a team of 5 Reiki masters and energy workers, together!
There were lots of issues in this home. It was build on a sacred tribal site in Canada, to begin with. This means, that to the first nation tribe, that land was communal, rather than owned by anyone. Then, there were issues with wealth and ownership of possessions to clear. Not exactly an easy project.