The Desirability of Agreement

As difficult as it is to achieve, consensus means everyone is more or less on the same page about the best way forward.

But does limiting our approach to a single favorite have downsides? What if the way we agree on isn't the best way? What if it doesn't achieve our desired outcomes?

Do we start over? Do we double down because of the sunk costs and pursue a sub-optimal path? Do we try a different idea?