Recently I have found that I can make custom enchantments with the command block. It seems that all armour is loosing the same amount of uses as they are without unbreaking. I have tried putting this enchantment on them, level 100 with the command block and no matter what, they still take the same amount of damage as a regular set would. I have tried the same with tools and weapons also and they took no damage several times. I have images of what has happened and here they are:
MC-52429
My boots semm to be loosing durability faster than others even with custom enchantments from command block
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The Unbreaking enchantment reduces the changes to be damaged, it won't prevent it.
According to your screenshots your boots are least damaged of all armor.