Question : Should Sys Admins (Domain Admins) also have user accounts?

In every place that I have worked Sys Admins have had a privileged account and a user account.  Generally, Sys Ads were to log onto the network with their user account, and use 'run as' to do Sys Ad work.  
I decided to do a little research, and am not finding much on this.  Why would Sys Ads be required to log in as a user, and use the run as command.  
I am looking for your opinions, what your workplace does, as well as references as to why this is the best practice.
Thanks!

Answer : Should Sys Admins (Domain Admins) also have user accounts?

If the printer is connected via USB check to see if the user changed the USB port the cable for the printer was plugged into. If the user plugs the cable into a different physical USB port then the logical printer port in Windows will be changed to match.

Ideally you never want to rely on user machines for services that other staff will need access to. I would consider connecting the printer to a print server. Assuming the printer is USB, these are readily available (USB Print Server) Once you've assigned the print server an IP, you can then setup user machines to print to that IP. When each user logs into TS they will connect their local printers and be able to print without issue.