Healthy disagreement

A 100% ratio of agreement could show that either the idea receivers don't think for themself, don't pay attention, or worst, don't dare to speak on themself.

A too low ratio of agreement could show that there are too much unknown variables, unaligned background, or a toxic debating culture.

There is no such thing a right ratio of agreement. However, the point here is that a complete agreement is not necessarily a good sign.