You can get 50/50 account wide, in fact you pretty much have to do it like that if you aren't playing a core profession.
As someone who has VQed cantha and completed the Cartog title, Yes, you will most likely need to scrape just about every corner when you vanquish. There is about 2% leeway with this title and that INCLUDES special zones that are not accessible without Heart of Shadow. The best way to do this title is, as Marty said, use TextMod. I'm going to be using it while I vanquish Elona (when I get around to it). It isn't too much work anyway, it takes maybe an extra 5 - 10 minutes depending on the zone. If you think about it, 5 minutes vs not scrapping and going back AGAIN to scrape and have to kill crap.
Wikis are also a useful tool, use them
