Sounds like the makings of a conspiracy film. I will look into it of course. From what I understand/remember dura loss is defined by damage taken with a little RNG. Dura is stored as a number in the thousands where 1000 = 1 visible dura, so a fresh ring has 5000 dura. This number is rounded (it maybe truncated which would explain the conspiracy..) which means that as soon as you get to 4.5 it actually displays dura 4. My point is, with the way it is displayed actually dropping to 4 isn't quite as dramatic as it seems and it will take much longer to drop to 3 after that..
Let me look into it!