Projects are like painting on canvas. Few decisions are arbitrary; others are not. Few decisions are difficult to change. While we have a vague understanding of the end result, the destination, approach and outcome can vary. It makes sense to start with a Minimal Viable Product (MVP) and refine it for perfection. Estimation is mostly a rough guess. Adopting what you have and adapting to the constraints and limitations is a sensible act. Sometimes you may feel like quitting. However, there is value in persevering to complete. Indeed projects are like painting on canvas!