Situations:
- On Small scale (or smaller than default), units will take forever to degrade enemy armour

- On Extreme scale (or bigger than default), units will quickly loose their armour

Root cause:

Armour degradation in probably a fixed value that gets lowered by each model being hit, regardless of Unit Size

Proposal:
Make Armour degradation thresholds to scale with Unit Size

Replays where you can clearly see the difference:

Armor at Small scale.replay

Armor at Extreme scale.replay