Like a daisy’s petals, research is described as cyclical and fluid. As we research, we may find ourselves returning to and changing our question, or we may near the end of a project and think we’re done but discover we need to go back to find more or better sources. The messiness of research requires us to be flexible, often modifying our approaches along the way.
I can attest to this as many times before I have changed my original question or approach after uncovering some bits of research.