Initially the judging is independent by 2-3 judges, and we don't talk while we fill out the scoresheets. Grunts, moans, 'wow!' remarks are deeply frowned upon. We should be doing it uninfluenced by the other judge. Definitely no table talk while the sheets are filled out. After arriving at a number we then compare and try to get the scores within some range which is instructed to us by the judge director prior to the start of judging. Usually it's 5-7 points max.
After discussion, the judges might make a few quick additions or edits to their scoresheets .
And it's true, after a couple beers the judges will often end up in lockstep and after judging independently will find that they are making the same comments and scoring them the same.
If you really want to learn about how beer is judged, volunteer to steward at your local homebrew competition. They are always looking for help. It's a great way to improve your brewing too, with the knowledge you pick up from hearing the entries discussed by the judge panel. Generally, the stewards are poured a sample right along with the judges.
As I understand, in BJCP events there are two judges that judge a beer. Do they discuss the beer together when assigning scores or do they judge the beer completely independent from each other?