I was recently asked a practical question about my approach to the prayer book tradition. For services at Christ Church, I write out most of my prayers beforehand -- for the call to worship, the prayer of confession, the prayer for illumination, and the closing prayer. There are a couple of other prayers that I don't compose beforehand -- at the offering, and at the Table. I have doing this for a number of years, but for many years before that, all my prayers were extemperaneous. So if I write my prayers out now, then why not use a prayer book?
Here's a quick take. Extemporaneous prayers are usually well-meant and heart-felt, but not thought through. After I began composing my prayers, one surprising result was that I found myself repeating myself far less. In other words, in my experience, written prayers were not an exercise in vain repetition, but rather a deliverance from it.
Written prayers (by somebody else, dead for centuries) are almost always thought through (and often glorious), but easy to not mean, especially in corporate public worship. Now it is no objection for somebody to write in and say that he means it plenty, for if you do, then God bless you. I am simply thinking (out loud) about large groups of people and the trajectory of things over the course of decades and centuries.
If I am asked to pray at a service, and I pray extemporaneously, thinking it through beforehand is optional. If the prayer that I will pray in printed in a book, and the ribbon is in the right place, then thinking it through beforehand is optional. Now when someone takes his duties seriously, and prays thoughtfully (whether extemporaneously or from a prayer book), I have absolutely no objection. I just want to point out that if I compose my own prayer beforehand, thinking it through is not optional.
But part of thinking it through means that I must think through how the congregation with me will respond to it as they hear it for the first time, and have to say amen on the fly, as it were. That's a reasonable objection, but it appears that first century saints knew how to do it, provided the speaker kept in mind what the apostle warned them about (1 Cor. 14:16). And I also grant that a healthy congregation in the prayer book tradition has the option of memorizing the prayers over the years so that they do know what is coming -- they have known for years. That's a good point, and when it actually happens, then again, God bless everybody.
But for my money, when the one who will pray writes out his prayers beforehand, this strikes the best long-term strategy for balancing thoughtfulness and sincerity. This is important, for John Bunyan once said that it is better for your heart to be without words than for your words to be without heart.