(When the Lord gave the instruction here, is it an icon to be worshiped, or a method to be taken and repeated over and over? Perhaps as one is learning, in the beginning, and Jesus wants you to know the basics of the foundation of prayer.)
However, I don't think God wants repetition to be the form of worship and communion with Him. I believe God wants a relationship, and while basics and repetition initially are good building blocks, they should not replace a relationship with God, personal and daily including the original and unique words you speak.
As the Spirit leads us 24/7, we will pray accordingly, and so in this beginning please understand that you will grow, and mature, being conformed to the image of Christ. )
Let us look closely at these verses bit by bit:
“And he said unto them, When you pray, say… .”
When the disciples asked, Jesus answered them immediately. He didn't have to think about it or meditate on it, He was prepared already and began to teach:
When ye pray, say, Our Father.
Our Father, this is what Jesus said to a group of brothers and sisters who never even considered God as "Father".
I believe, that Jesus was not only speaking to the use of the phrase "Our Father" but to the basic spiritual foundation he lived on/in/through/for -- Our, Father. One we would do well to move in. The basis for our new life is the Father heart of God, and this is the place we come to in order to begin our new life.
“Who art in heaven”
To clear up any doubt about the “Our Father”, Jesus simply acknowledges the place where God is. This is not in dispute with God the Father, the Son, Jesus, and the Holy Spirit dwelling in our heart, but that is more for later. Right now Jesus was sharing an awesome powerful truth, and I believe He wanted no doubt as to God being the "Our Father".
Having said that, I now ask you to think a moment. Is a teaching to be lifted up and repeated verbatim, or is a teaching, perhaps, a living growing truth, that cannot be hammered (forced) into any particular pattern? If so, then learn as a child learns, repetitively, but not hammeredly. Remain simple in your approach to prayer, and God through His Holy Spirit, will lead you into all truth each and every new day.
This is how we learn in relationship with God. The absolutes are not the legal demands, they are spiritually alive truths. As such, they cannot be erected as shrines of worship.
God and His Word (Jesus is the living Word) and the Holy Spirit of Truth are one, a mystery that only God can reveal. This is a spiritual dynamic that is learned; taken, eaten, digested and distributed to all parts of our new spiritual creation, us, as God purposes and plans. So, let go and let God or as a friend in Jesus once said to me - Let Him.
“Hollowed be thy name”