Most things I work on professionally are 4K for a 1080 delivery, so you really don’t need Proxy with a fast enough RAID and mechanical hard drives, but my experience with 6K DaVinci Resolve RAW footage I have realized that a proxy workflow may be back in my future.
The problem is that for VFX work I need to work with RAW and my iMac Pro with only 64 GB of RAM is really starting to show it’s age.