One of the major challenge in the commercialisation of fusion is maintaining the powerplant reactor in a sufficiently short period of time to achieve commercial levels of plant availability. To inform the development of an appropriate remote maintenance strategy for EU DEMO, a simplified, parametric model, called the Maintenance Duration Estimator (MDE) has been created to model potential remote maintenance strategies for the In-vessel Components. This tool will inform the development of practical and efficient remote maintenance technologies and methodologies for EU DEMO. Using the MDE model, it has been estimated that DEMO will be able to achieve the required minimum 30% lifetime plant availability over a 20 year operational lifetime. Here we will present the structure and functionality of the MDE, as well as some case studies of analysis performed, including the comparative assessment of two candidate pipe cutting and welding technologies, the remote maintenance feasibility of a Double Null configuration of EU-DEMO, and an initial cost benefit analysis of increasing the parallelisation of EU-DEMO breeder blanket maintenance operations.