Cussing is an art, of sorts. It really doesn't have much shock value to pepper a story with cussing. Actually, it slows the story and is quite boring after a while.
A few years ago, a writer argued with me about the amount of the F-word in their manuscript. The point that I was supposed to get was that it was the 70's [in the story] and that made it correct. I was around in the 70's and people didn't really talk like he wrote in his story. Actually, today's vernacular is more vulgar than in the 70's.
Cussing has to fit the character and the situation.
Besides the fact that too much of a good thing ain't so good, it gets boring rather quickly. This is true of any word or phrase that is over used, and especially true of cussing. Most writers have a pet phrase or word that they over use, which is a good reason to have someone who knows what they're doing point that out to you before you submit your ms to a publisher or literary agent.
Excessive cussing simply isn't good writing. If the character's main contribution to the story is to spew cuss words like a drunken sailor every chance they get, that character either needs a bar of soap to his fictious mouth or to be cut out of the story completely.
Even if the point is to show a drastic conversion of character, it is a pretty flat character who is defined largely by their potty-mouth. Write like a pro and give the poor fellow more dimension to make him interesting.
The other point of this is that the cussing needs to fit the situation. Like everything else about fiction writing, the cussing needs to be believable. It needs to occur, if at all, in a situation that is logical to the reader.
Write better, use your vocabulary (or get one), and minimise the cussing. Raise the bar. Write right, damnit. (Just had to do that to make my point.)