It took me about 5 minutes to use UUP Dump to both download and create an ISO.
Now I am upgrading a Hyper-V VM via Windows Update, and it took a full 3 hours to get to the Restart and after another hour (4 hours total, so far) it is at "Working on Updates 23%" after the Restart. This VM has 6 CPU cores and lots of memory available
to it. It seems to be moving along now, so maybe it is almost done.