Suppose you have discovered a user account that contains a significant amount of plagiarized contributions. There are hundreds upon hundreds of answers to check, and you are willing to do that, stretched over a period of time. (Although you ask yourself whether there is a point - seeing as there are probably thousands or tens of thousands of users on SO that operate the same way.... but that's a different discussion.)
What is the preferred way to report these?
Flag each plagiarized answer separately, as they come up (the current status quo I think)
Flag each plagiarized answer separately, as they come up, but point out that they are part of an ongoing series
Collect plagiarized answers somewhere (where?) and report them to mods when you are done
Some other way?