The 1915 (Viente) 20 Centavo, High Vs, Low Star Relief.

is what I feel like when, after I graded a coin as low relief and find a similar one graded by a top grading company as high relief. I realize coin production occurs at a rapid pace and that not all coin blanks will end up having a perfect impression given the abuse the dies are subjected to with each strike. As the dies wear, the sharpness of each succeeding hit becomes less pronounced and at some point the dies are replaced. After reading the available material on-line and speaking to other collectors, I believe there is no definitive way to properly grade this coin. One grading firm decides a specific coin is MS64 and a coin which appears identical is graded MS62. High relief star supposedly will suffer weaker striking of the key and palm tree, yet I have not read any testament that a low star relief will have a bold key and palm tree. My point is this: Graders decide whether a coin is high or low relief and impart a number grade based upon some set of standards, so just because they say it is thus doesn't mean they are right. Does anyone in the community have a definitive means of determining high vs. low star relief?