There is a reason for standing before an audience of God’s people and preaching or teaching.
There is also a reason that some are more effective — and far less effective!
There are those who are so consistently effective that people tell other people about this-or-that message and or their preaching/teaching ministry.
That is exactly the “#1 Test of Effective  biblical communication.
Some like to say that they are preaching to an audience of one — and that is accurate regarding the content of what is being said. We are called to preach what the Scriptures teach, not what God’s people would like to hear said.
The truth is that none of us are preaching to only that audience. Rather, we work hard at message preparation because there is an audience beyond that One who doesn’t know about our preparation, thinking, and heart as we prepare.
Nevertheless, there is a reason that classes, books, seminars, associations, and conferences focus on the academic topic called “homiletics.” Because we can and should improve. Because there are those who are really effective; in fact, we even listen to them! Because we all seek to exert a biblical influence that has staying power!
As we all know (even if it doesn’t seem like we/some do). The measure of effectiveness is not
- how many slides are used
- how many blanks are on the distributed note-taking form
- how many of those blanks were filled or correctly filled in
- what people say while greeting them at the door
- what your wife tells you
- what we think was or was not a good / bad sermon
The #1 Test Of Effectiveness Is Retellability!
The #1 test is whether someone
directs others to hear a sermon or
repeats the driving idea or a key point of a sermon.
√ Who hasn’t directed others to listen to the Alistair Begg clip in recent months! 
√ How often was the clip by S. M. Lockridge passed around and listened to by those who do not even know that Lockridge died 22 years ago 
√ What sermons do you remember, cite, or even “repeat” when you are preaching/teaching?
Perhaps, “Retellability” is one of the best tests of effectiveness.
- Do those who listen to you direct others to listen to what you have to say?
- Are there “takeaways”/ “repeatable” that stay with the listeners after — well after — the sermon?
- Is there something worth retelling — to oneself and/or others?
- What is repeated by the listeners still years later?
- What do you retell, and/or “repeat/restate” in your sermonic ministry? 
- Have you wished that you had come up with that way of making and wording a sermonic point because it is so effective — so retellable / repeatable?
- Have you said or heard said . . . “He is Good! You should listen to him!”?
- Do others retell it to others?
1. I use the word “effectiveness” and not “successful” for a reason. We are called to be effective communicators because there are situations where one is effective but not successful. The field of endeavor is a very difficult place to be successful if “successful” means having a meaningful impact. There were situations where Paul was not very successful, but he was effective.
2. What preacher/speaker hasn’t heard a great response to a message we thought went badly.
“That’s My King” — around the 54-minute mark
5. i.e. — “If we could lose our salvation, we would!”