I use getdefaultprinter.udf in my user login script. I record the printer to a file on a server so that I can look up the default printer for computers if needed. This way if someone new signs onto a computer and wants a printer installed or if the printer is deleted, I know which one to install. I use this mainly for reference.

For shared computers, I use different scripts to add and set default printers using Active Directory groups of some workstations for specific printers. I don't use this for computers that have only one user.