In Mark 3:14-19, Jesus separated twelve disciples unto Himself and the reasons for His action were expressly stated in that passage as:
1. To be with Him.
2. That He might send them to preach.
3. To have power to heal sicknesses and cast out devils.
The reasons as given above can be categorised into two: primary and secondary, the first being primary and the last two being secondary. The last two are secondary because the rudiments for their effective execution depend on the first.
It is in being with Him that they will learn His ways and acquire the necessary skills required to preach the gospel and receive such power that could heal sicknesses and cast out devils.
It is in the light of this that Jesus regularly had behind closed door sessions with His disciples (John 18:1-2). These were not just appraisal sessions but periods of spiritual impartation. Times when the deeper things of the spirit are exposed to the disciples by Jesus Himself, when the parables are explained in clearer terms, when their spiritual swords are sharpened and their horn filled with oil to the overflowing.
The testimony of the pharisees about Peter and John testified to the fact that those meetings of Jesus with the disciples were far more than just an exercise to keep them busy or an avenue to milk them dry (Act 4). The most essential point of discipleship therefore is the empowerment of the disciples.
The questions therefore arise, why do you raise disciples, how often do you meet with them, what are the subjects of discussion when you are alone with them? If the disciples must do greater works, there must be great experience of deep spiritual impartation.