When this question is presented, I quickly go to 1 Corinthians 13:9. I really like the way the Amplified Bible translation puts it, saying: “For we know in part, and we prophesy in part [for our knowledge is fragmentary and incomplete]. The reason I go to this scripture is to first establish that Paul is writing "we know in part". Our knowledge is incomplete, but that does not mean we are not aware of particular things. Our knowledge is fragmentary, meaning broken or small. Our minds cannot understand the total power of God, however, there are things we do know.
Have you ever gone to an amusement park? If you go to an amusement park and get on the roller coasters and you get on another and then another, your adrenaline will kick in. When your adrenaline kicks in, you'll find yourself going on roller coasters you didn't even think you'd get on. You didn't lose control of your feet. Not your hands or eyes. You didn't lose the scenes of smell, we know this because now when you smell cotton candy it reminds you of the craziness that was that day. You got up on the roller coaster and not once did you black out, see you where well aware of what you were doing.
I use this illustration to say that when you preach you don't black out, but rather a force known as the Spirit of God is leading you. You see the peoples faces and notice their body language. You hear the baby screaming at the back of the church and you definitely feel your knees buckle, even just a little. Considering that this is so, we must be aware of time and understand that time is of the essence.