The voluntary economic subordination to the Godhead of Jesus through Incarnation, for the express purpose of our salvation, is no longer current. His mission has been accomplished (unlike some other!). While He was on earth, it was proper to pray to the Father because of that. But where does that leave the Giver of Life? If we are going to distinguish our prayers according to the Godhead's economy of our salvation, we are creating a Tiered Trinity and therefore an unholy one. God is one despite His economic subdivision. As the Creed says all three together are worshiped and glorified.
“But where does that leave the Giver of Life?”
In His mediatorial function (His “session”) until the “fullness of time”, seated at the “right hand” (seat of power) of God as our High Priest, “Far above all principality, and power, and might, and dominion, and every name that is named, not only in this world, but also in that which is to come: and hath put all [things] under his feet, and gave him [to be] the head over all [things] to the church, which is his body, the fulness of him that filleth all in all.”