The church is told to "make disciples". Jesus demonstrated that one of the ways to be effective in developing disciples was to actually spend three years with just twelve of them. Jesus and his disciples were together in the desert, on the mountains, in boats during the storm and through some difficult times.
Often there may be short cuts we can embrace but typically while we may be convinced we are being efficient, we aren't necessarily effective. I lived in Mexico for almost three years and I learned that particularly in Latin America, developing relationships takes time. It takes time and effective leadership that allows us to transfer skills and a passion for people. To effectively train and disciple others we need to provide feedback, offer suggestions and demonstrate support.
If our objective in ministry is to train and develop others that are to become effective in ministry then we are following the Biblical mandate. Christ gave us (who are called to lead in ministry) "to equip His people people for works of service, so that the body of Christ may be built up" (Eph 4:12)
Now that's being effective!