When product development projects involve many different moving parts, it can be difficult to keep track of how much time and money is being spent on each task. This is where time and materials billing comes in. This type of billing allows businesses to keep track of the hours spent on a project, as well as the materials used. This information can be used to create a more accurate estimate of the project's total cost, and can help to prevent overspending. In addition, time and materials billing can help businesses to better understand the true cost of their product development projects. As a result, it is a valuable tool for businesses of all sizes.