Computer building time has so many variables...
If it's just a decent case with fans properly preconfigured, mobo, CPU, easy to install air cooler, RAM and PSU plus a m.2 drive with the OS already preconfigured on it and I only need to function check as far as being able to go into bios, see all hardware and enable XMP, half an hour is doable.
Now if it's a bit more complicated of a case with a GPU and RGB that needs to be tidily cable managed, I need to do a burn-in test with a test OS before installing the final drive, there's multiple drives and a AIO that needs to be mounted or even a custom water cooling loop that needs to be built and leak tested? Yeah, that's gonna take a couple hours. Or even days, if the custom water cooling is supposed to be extra fancy.
If it's just a decent case with fans properly preconfigured, mobo, CPU, easy to install air cooler, RAM and PSU plus a m.2 drive with the OS already preconfigured on it and I only need to function check as far as being able to go into bios, see all hardware and enable XMP, half an hour is doable.
Now if it's a bit more complicated of a case with a GPU and RGB that needs to be tidily cable managed, I need to do a burn-in test with a test OS before installing the final drive, there's multiple drives and a AIO that needs to be mounted or even a custom water cooling loop that needs to be built and leak tested? Yeah, that's gonna take a couple hours. Or even days, if the custom water cooling is supposed to be extra fancy.