Being able to swim in a swimming pool might not mean that one can swim safely in the ocean during a hurricane. Skiing easily on an intermediate slope might not mean that one can ski easily (or safely) on an icy, advanced slope. Similarly, being able to have an easy conversation about what is going well might not mean that one can effectively or safely have a difficult conversation about what is going poorly or concerns about future plans.
I've found the concept of "conversational capacity", as described in Craig Weber's 2013 book (with that title), to be extremely helpful in my work with coaching and consulting clients. As Craig describes it, if one were to rank a list of conversations from easiest to most difficult, one could probably draw a line somewhere in the middle of the list where conversations below the line would fall within the group's (in many cases, it may just be 2 people) conversational capacity.
I believe that the conversational capacity of a group is highly influenced by the capacity of the group member with the lowest capacity and, to some degree, by the capacity of the group member with the highest capacity (roles and power play an important role in this, as well). So, improving conversational capacity is both an individual and group project.
I've written previously about some of the techniques involved in building conversational capacity (How to increase your conversational capacity and why it's so important to effective decision-making) but am now realizing that a clearer explanation of why this is important could be helpful. If candor is missing, important points may go unsaid. If curiosity is missing, the group may miss opportunities to understand points of contention and to find better solutions. Without a sufficient level of conversational capacity, a group is likely to avoid discussing topics and/or to have ineffective, unproductive discussions, unable to make significant progress.
Conversely, a group with sufficient conversational capacity can discuss contentious topics productively, coming up with better solutions that take into account the potentially valuable input of those taking part in the discussion.