Yeah, using these percentages to see when and how much to bluff are great guidelines. But from my experience (as I don't have such tools) if I can see a guy play a few hands that go to showdown, I generally have a good read on his thinking patterns in case I want to calculate if a bluff would be successful or not.

Whether to bluff or not depends a lot on the preflop raise, position (because in bluffs it is essential to have information on your opponent's hand) and the particularities of the flop. As an example, if I know this guy likes even a MP, then after a preflop raise and a flop that could very well have given him "something", a medium-sized bet to bluff/c-bet him out is a bad idea. I would need a huge bet to bluff him out of his little holdings, which is ofcourse stupid against this sort of player for cost/pay-off considerations. Against a player who on the other hand plays a more cautious game (ie fold below TP) then a c-bet or a bluff after he checks is more of an option.