This is what I hate about MS documentation and such functionality. There are (from what I can make out in the documentation) large databases where any performance improvement of CHECKDB would be a help. Since they are large databases, they're also partitioned with one file/filegroup per historical month. According to both your and my interpretation of the trace flag you speak of, it's not going to work anywhere on the server because it's a GLOBAL trace flag.
Hmmm.. maybe I can just turn it on when I need it and off when I don't.
Still, even if every database had multiple files, their requirements for usage make doing tricks like my previous answer, which is extremely beneficial where I've done it on some really large CIs, either make it so you can't use the trace flag on that database or make it so you can't get the benefit of the method I posted.
I keep the benefit of what I posted.