You can upgrade using group policy and the executable or a 3rd party program which will do this, but unless you have more than 10 to 15 computers, you are probably better off upgrading locally.
If you use RDP with the installer on the server or a location which can be shared, you can literally remote to each, run the installer, and even while it is installing, remote to another computer. That is the way I do it, and it takes about 20 minutes to do eight work stations.
If you really wish to do it using group policy, then you would have to contact Sandeep.
Usually takes me about an hour to do about 8 computers. I would be interested in more info about group policy and executable (or 3rd party program.) Sandeep (since Bert put you on the spot) (or Bert) could you expound please.