issues with updating to Ventura from iMac

There are many factors involved to list every possible combination.

1 - How much empty Space is on the Drive ?

2 - Is the Drive a Fusion Drive or Mechanical / Rotational Drive or ALL SSD ?

3 - Is the current version of Big Sur Fully up to date ie Big Sir 11.7.8

4 - Is there any Third Party Security Software used and Installed on this computer ?

5 - Is the computer connected to internet via Wifi or Ethernet cable to router ?

6 - Technically, if the computer Qualifies to run Ventura, you can skip the step up to Monterey and go directly to Ventura

Personally, I tend to avoid skipping early upgrades but that is my choice

Have moved from Monterey macOS 12 to macOS 13 Ventura on 2 M1 Computers took about 60 minutes from Starting to download to final reboot into the New OS

On a fast connection, about 40 to 45 minutes.

Relevant information omitted

All Done over Fibre Optic to Router connection and over 5 gHZ wifi connection.

No Third Party Security Software and No VPNs involved or used