There are many times when we need to speak up and make sure we have communicated with others concerning our concerns. Mature adults ought to be able to have adult conversations and work to resolve conflicts, which always involves speaking and listening in love. And, since we are raising children to become adults, we should also be training them in this necessary work.
This does not, however, meant that everything that could be said should be said in every situation. As those who are pursuing peace and who cover sins with love, there are many times when we should not say what we're thinking. Sometimes this is simply a matter of kindness and courteously. At other times its the evidence of wisdom. The fact that something is true does not mean it must be spoken. Moreover, even truth can be used in such a way as to harm others or exacerbate a bad situation. Tongue-biting is often a grace (James 3:2). We are called to edify with our words; even the words of disagreement (Eph. 4:29). The use of our words, which like other tools, can be used to build or tear down; to improve or harm. Wisdom insists that we make sure our words are used to the glory of God (Col. 4:6).