Kevin Hill has a video for us:
Query multiple SQL Server instances at one time!
I have used registered servers before, though my strong preference is for a Central Management Server. There are limits to how many servers CMS can handle before the initial load gets slow—I know this because we’re over the limit and it causes SSMS to freeze for 3-5 seconds the first time I open CMS. Still, having that server list in a central location means not having to share files around with the rest of the team and trying to figure out whether you have the most recent version of the file.