You are right, that procedure is supposed to work, but unfortunately it doesn't... In the end the only thing that I've found to work 100% of the times is small utilities like NoSleepHD2.0, that writes an empty txt file every few minutes, so your external harddrive can never go to sleep. Works with autostart, so you don't have to remember to run it at every boot (run it as admin).
I've upgraded from a mechanical 2Tb external HDD to a SanDisk Extreme 2Tb SSD. It's super fast when in use, but when I'm inactive for a period of time (as little as a couple of minutes) it seems to enter some sort of sleep mode. Any activity that would use the drive takes a long time to get going, often 10-20 seconds, but then it's full speed again. That makes anything mundane like copying files very slow - particularly because Windows "locks up" whist waiting for the drive to get going. I'm now on Windows 11, but the problem was there with Windows 10 too. Is there a way to stop the SSD from entering sleep mode (if that is what it is)?
XPS 9310 & SanDisk Extreme 2Tb SSD: sleep mode?