You missed my point....input from an LEO will often give you better insight as to where that "line" is that goes from "maybe jail" to "enjoy the ride". Subjective, to be sure - but sometimes those subjective opinions can be helpful.
The line is a tool of the trade. It has no definitive position. The difference of going to jail vs not, as much as we think it shouldn't, could be the officers mood at the time of the stop.
Helpful as in knowing what officer X does over what officer Y does. But unless you encounter X or Y. Its not helpful. A city you are stopped in, might subscribe to the, "Broken windows Theory". And another town, your stopped in, might not. It will be two distinctive ways of how they apply the law. So to ask the officer where the line is in the first city, will be different then the line in the second.