So I think it best to start with the shape of the text as the default shape for the sermon. But that may be adjusted due to the needs, nature and situation of the audience. One other factor should be mentioned too:
Factor 3 – The strengths of the preacher. Another factor to consider is you. Are you able to effectively keep attention and hold the tension of an inductive sermon? If not, it may be better not to try, fail and lose your listeners. Equally, we do need to try and fail in order to learn. It is worth considering your own ability as a preacher, but please don’t let this be an excuse to always preach the same shape!
Every time you preach you choose which sermon form to use. Start with the text shape as your default, but feel free to change your strategy in light of your listeners and yourself.