There is a big difference between having our agenda set in a cognitive fashion and an agenda that comes from the Holy Spirit. Both can be legitimate and both can result in a dynamic prayer life. However, it seems to me that the "Spirit led times" are more effective and efficient. It also follows that those praying are more likely to follow up and act accordingly when they hear God's voice and not just the call of a human to act.
As St Paul said, "I will pray with my spirit and I will pray with my mind also. I shall sing with my spirit and sing with my mind also." ICO 14:15
When do you find yourself most open to the touch of God?