I have seen very few pastors preach without notes pre-written. The only ones are on TV pastoring mega-churches. All songs and hymns any congregation sings have been written beforehand with a predetermined melody. And those songs were written with the help of an instrument to sort out proper chords, even if you are singing a capella. Worship is directed to be in order, which must be predetermined. The Holy Spirit should be present when any of these planning phases are happening.
For many people (myself included), public speaking isn't easy. Public speaking without any kind of notes would appear to be on the verge of terrifying. I've served in the preaching of the glad tidings for a few years now, and it doesn't get any easier, and most brothers would say the same. But what I have found is that the word is clearer and more powerful as I rely more on the Holy Spirit. The more dependent I am on Him, and the less I try to memorise the terms of the gospel in the mental way, the more effective the word is. That might seem an obvious thing to say, but it is the natural tendency of many of us to rely on oratory and forms of words. But, as we get older and grow in our knowledge of God, we learn to trust in Him more and more, and ourselves less and less. This year I've been privileged to serve quite frequently, and a number of brethren have said to me that they're glad to hear that I've been helped in the preaching. Not to hear good things about my preaching, or that I'm a good preacher (because I certainly am not!), but that I've been helped. I've proved the Spirit's power. I'm glad to be able to say that. Well, that's enough about me. I've talked about myself more than I like to, or is profitable.
As for music, we have to be practical. The hymns and songs we sing have been written down beforehand, by people who've had an impression of God and written it down in that way for use in His praise. The brethren with whom I walk in fellowship have a hymn book, a collection of hymns and spiritual songs, chosen after a great deal of prayer and soul exercise. We're all familiar with melodies that we can sing these hymns and songs to. Even in this though, there's scope to allow the Spirit of God freedom in the assembly. At the Supper, for example, if the Holy Spirit brings to the mind of brother or sister the line of a hymn or song, or the impression expressed in the hymn or song, a brother announces the number of the hymn or song in the book, and then starts to sing it, and we all join in with him.
At the Supper, if we were to predetermine what prayers were to be prayed when, what hymns would be sung at what time, what scriptures would be read... what liberty is there for the Spirit, in the assembly?
It's wonderful for us to be able to come together, and having broken the bread and passed it from one to another, and having taken the cup and done the same, to be led by the Spirit in praise and worship to the Lord Jesus, then touching on praise and worship to the Spirit Himself, before moving on to worship of the Father, then to God, the Triune. The Spirit is free throughout to lead us to sing a certain hymn or song, to lead a brother to pray, or to share a scripture or an impression. We don't decide who goes to the table to break the bread, the Spirit does. He is free in the assembly, there and then, to direct our worship. The result is wonderful life, freshness and spontaneity, and a taste of heaven, the sphere where Christ is in glory.
I could not, in good conscience, have it any other way. It isn't just that a pre-ordered service, with pre-written thoughts and impressions would be less full of life and spontaneity than a service led by the Spirit. It's the fact that a divine Person desires to direct our worship actively. If we try to determine the order beforehand, we put Him out of His place. How grievous that is to Him, to be replaced by a committee or a director, regardless of how godly these people or person might be.
Well, these are just a few thoughts on a very holy and expansive subject. I want to make it clear that in making these observations, as always, I'm not intending them in a critical spirit toward other believers. Nor am I claiming some sort of higher ground. These are simply my experiences and convictions, which I hope will be profitable for the brethren, if the Lord will.