Thanks,
There is a particular way that you need to use Recuva to recover the files that were on a drive that has become RAW.
If you have not used that special way then your scan is looking for every file that might ever have been deleted from the drive.
How long a scan will take depends on a few things, but mainly the speed of the connection (USB3 is faster than USB2, SATA is much faster than USB) and the capacity of the drive.
It’s just a consequence of todays much larger capacity drives, there is much more memory to be scanned on a 5TB drive than a 500GB one. (10x more so it will take around 10x longer to scan)
See this for how you should recover the non-deleted files from a drive that has crashed/become Raw: