Your conclusion may be correct. However, I am in this older class (age 75) and still prefer to keep my INR around 3. My doc likes it a little under 3 and I like it a little above 3....so we settle on "around 3". My experience is that my warfarin dose has declined over the years due to aging and activity decline, in order to maintain the INR of 3. Unfortunately, INR results are far from an exact science and depend on many everchanging variables, from recent diet, activity, testing nurse protocals, machine tolerances, weather(?) etc. My range has always been 2.5-3.5 and I try to stay away from the upper and lower limits, but I do not, and cannot maintain a "close tolerance" target. My experience has been that compliance that maintains an INR within a reasonable range will minimize a nasty event. According to the docs I have talked with, NON-COMPLIANCE is the major cause of problems with warfarin....and I can personally attest to that. People who take warfarin as prescribed and test routinely normally have few, if any, problems. That said, there are always exceptions.
BTW, when I begin to experience noticeable bruising or excessive bleeding, I will probalbly reduce my INR to "under 3".....but so far, I have not noticed either of these problems.