Effective communication is a two way process with both the speaker and the listener being equally responsible. An active listener will pay attention and respectfully ask for clarification if he/she does not understand. An attentive speaker will try to make his point clear and precise but realistically this is not always possible because of complex subject matter or perhaps being nervous perhaps. Many things can affect good communication but it can be achieved with all persons wanting the same outcome, and making the effort to be involved.

Sometimes effective communication is simply impossible, listening to a speaker who drones on and on and on, makes it hard to listen when your eyes get heavy, and you think "I really wish I were anywhere but here."

No doubt, they are both.

Hi, DAICHI, it's true. I know Europe people and American or Canadian people are likely to explain what they think, why they do, to make themselves understand. Sometimes it might sounds like their too much excuse for what they did. But I realized that they seem to think it's rude not to explain and excuse. They think the listeners have rights to listen to the explanation, the reasons, the ideas, the details and so on. On the other hand, Japanese people think it's beautiful and respectable manner to guess or understand before listening the whole contents.  Moreover,  in Japanese society, if someone explains too much, his attitude would be looked arrogant or annoying. I think this is one of the reasons that  Japanese people are not good at discussion. Japanese people tend to be quiet and wait for being understood them without their talking. It also causes that non-Japanese people often confuse why Japanese people don't say anything. Personally, I prefer non-Japanese way because I often failed to guess and understand people who didn't explain to me well.