Muscle Armor effectiveness

[Dan Howard]

A leather musculata, or any kind of cuirbouilli is pretty much useless as armour unless it is layered over something else. In the Middle Ages it was pretty much always worn over mail. Do we have evidence for muculatas layered over mail? Leather only makes effective armour by itself if it is multi-layered. Overlapping plates, like scale/lamellar is another way to get a multi-layered effect.