Spontaneous or rehearsed? I think God likes it all, but I'm not so sure that people always do.
I like working in a worship band environment where there is flexibility that partners with a practised plan. Sound like an oxymoron? It may look like that on the surface but it is what we are to bring to any situation in life. God wants our best offering but we are always to stay attentive to His voice... 'cause His plans don't tend to be stationary.
Let me explain. As a band leader, I endeavour to do my best to be practised and to give as many tools to the team as I can to help them to succeed. I also want to honour those (as in, congregation or crowd) that we, as a band, will lead so I try to be as prepared and organized as possible so that I can engage effectively. Am I the best in the world at this? Absolutely not! But I come with my best in that moment to honour God and to honour the people that I work & have influence with.
During these processes, I stay connected with the Holy Spirit, asking Him what He wants. When I have established 'the plan' I continue with my antennae up toward God's leading. He may want to change or add something else and I want to be available for that.
Think of Abraham. God told him to take Isaac and give him as a sacrifice. (Genesis 22) What if Abraham had stopped listening to God's voice, thinking that he had the order and 'come hell or high water' would not let anything or anyone stop him from carrying it out? We would have very different history written down if Abraham stuck to 'the plan'. This is a great example of living in a constant state of awareness, praying without ceasing, walking in obedience and not quenching the spirit of Jesus. Life in Christ is not static. It is full of motion and full of wisdom. God gives plans and keeps building on them -- growing fruit.
If I were to compare spontaneous singing in a corporate worship setting to planned and rehearsed, I would suggest that for the most part there is greatest effect spiritually, intellectually and emotionally as a group when we are singing lyric in unison. There is strength and power and blessing in that type of unity. Declaration is made vocally even if it isn't felt emotionally. If, from that, there comes a moment where the voices start drifting spontaneously, almost as if there was an invisible conductor somewhere leading the group into beautiful, unknown territory, leading us off of the planned chart - I guarantee you that I will feel uncomfortable & vulnerable, but I will want to join the unwritten symphony. I don't want to miss the adventure! I will continue asking though for direction and will endeavour to ride the new song until the Holy Spirit says 'That's sweet! We're done now.'
So I come back to the beginning of my pondering... spontaneous or rehearsed. Right or wrong? I think the answer is in both as these are merely methods of delivery. What is important is what Abraham displayed, a posture of constant listening and quick obedience. Samuel said it as well ...To obey is better than sacrifice (1 Samuel 15:22). Let's be people that bring our best offering, both to God and His people, and in that let's also be people that never stop listening & acting on His voice.
What is the conclusion then? I will pray with the spirit, and I will also pray with the understanding. I will sing with the spirit, and I will also sing with the understanding. 1 Corinthians 14:15