The same way that our natural bodies need more than one nutrient to remain healthy and grow, our spirits are also nourished by multiple sources. This means that even though you may be very disciplined in Bible study and prayer, it is not enough. You also need to fast and practice solitude.
This holds true for more than the disciplines. You might be very involved in a small group, but still need to pursue a mentoring relationship. You appreciate your pastor, but have tuned out all other voices for spiritual guidance.
No one practice, person, or even group can provide for us the entirety of our spiritual formation.