Fourth Generation Principle in Discipleship

Searching for this principle on the internet proved to be fruitless.  However, in the past my training somewhere included this fourth generation principle. In essence, we have Paul, Timothy, faithful men, and others also. This principle is taken from 2 Timothy 2:2, “And the things that thou (Timothy) hast heard of me (Paul) among many witnesses, the same commit thou to faithful men, who shall be able to teach others also. If we take this principle to heart, every discipler should concern himself/herself with communicating the gospel to the third and fourth generation and not just to the present generation.  So, our goal in the Christian church is not just to evangelize and reach the present generation, we should be reaching and training those we have converted to become true disciples of Christ and to reach out to convert others, train them to be disciplers and so on.