Achieving consistency of Last Planner® System (LPS) implementation is a persistent challenge for owners, contractors, and practitioners alike. This research evaluated the application of all functions of LPS within an Engineering, Procurement, Construction Management and Validation (EPCMV) consultancy and sought to develop a Guideline and Implementation Health Check (IHC) to assist consistent LPS implementation across all company projects. The study adopted a mixed-methods approach utilising case study design and data collected from a literature review, project documentation review, purposeful semi-structured interviews, two pilot implementations, and a focus group workshop conducted within the case company and across two projects. Findings posit an implementation assessment tool (IHC) should be considered as an aid to sustaining consistent LPS implementation across projects. Construction should strive to standardise its processes (like the IHC introduction) and adopt a 'process improvement' view and mindset. The IHC highlights the critical components of the functions of LPS and allows project teams to check whether each is being utilised effectively. LPS and its functions constitutes a systematic process for construction planning however, best results will only accrue once all components are in place. While the IHC will ensure the physical infrastructure is in place, successful LPS implementation necessitates deeper consideration of how people think, communicate, engage, commit, and collaborate. Successful and sustainable LPS implementations must be founded on a desire and motivation to improve existing delivery processes and necessitate senior management commitment from all stakeholders.