When does cost segregation actually make financial sense

I am trying to understand in which situations cost segregation provides real tax benefit and when it is just extra paperwork. Some say it helps early in ownership to improve cash flow, others say it only makes sense for larger commercial properties. I would like to hear from people who have actually seen the impact on tax liability, depreciation schedules, and long term implications. Has anyone here used RE Cost Seg, and did the results justify the effort?