In the fight at the VOTE, Madara showed a Susanoo that is as big as his recently shown PS but it wasn't stabilized yet.
These two Susanoo are the same:
And this is a different one:
I think that the reason why Madara was able to stabilize his Susanoo was because of the Yang Chakra he obtained when he got a part of Hashirama's power. The Susanoo is mainly Yin, but to make something that is ethereal touchable you need Yang. That would be the reason why he didn't use the Stabilized Perfect Susanoo against Hashirama because at that time he still didn't have Hashirama's DNA.
This is a plausible theorie, and it might as well be false but I think it might be true!
These two Susanoo are the same:
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You must be registered for see images
And this is a different one:
You must be registered for see images
I think that the reason why Madara was able to stabilize his Susanoo was because of the Yang Chakra he obtained when he got a part of Hashirama's power. The Susanoo is mainly Yin, but to make something that is ethereal touchable you need Yang. That would be the reason why he didn't use the Stabilized Perfect Susanoo against Hashirama because at that time he still didn't have Hashirama's DNA.
This is a plausible theorie, and it might as well be false but I think it might be true!