Yes and no. The whole point of doing it blacklist way and NOT whitelist way in urlf layer is because IF you say had any any drop at bottom of that layer, ALL traffic would get dropped, as it has to be allowed on EVERY ordered layer. So say, just as a stupid example, if someone had 100 ordered layers and traffic was allowed on 99 of them and last, 100th layer had any any drop at the bottom, EVERYTHING would be dropped.
Makes sense?
Also, keep in mind that its better traffic processing for urlf blade when you do blacklist approach, because first network later, you allow traffic to the Internet, but since traffic has to traverse EVERY ordered layer, you block whoever you need to block from getting to whatever site in that 2nd layer you see in my guide.
Andy