I agree with brdad that hints should be left to the discretion, or the whim, of the cache placer. Laughing Terry gives his hints in a series. I think I needed 4 hints (and 5 trips) to get the cache on the 2 cent Bridge in Waterville. When folks call me for a hint I ask them straight out if they want a "little" hint or if they're getting frustrated do they want something more specific.
Personally, I try not to call unless I've put in a solid half hour or more and even then I'll often pass and try it on a different day or when I have "eagle eye" Dianne with me.
It's just another one of those questions best answered by reminding all that this is a game and how you play it is a matter of personal choice. Some players are what I call the "purists." They don't need or want any assistance and that's fine. One of my best friends eschews folks that hunt deer with a rifle, preferring a recurve bow like the early settlors used. Again, both "put meat on the table" and I'm not going to criticize folks who call for hints, as I do from time to time, as I find it FUN every time I find a cache, hint or no hint!
Sometimes the road less traveled is less traveled for a reason.