This paper looks at the different parts of the Critical Path and Resource Utilization (CPRU) heuristic for use in the Resource Constraint Project Scheduling Problem, with variable resources (RCPSP-t programming problem). RCPSP-t has many real-world instances such as in hospitals or manufacturing. Optimizing the solution generation for these instances may improve the efficiency of these industries. CPRU was split into parts and different versions were compared against VSIDS a more modern heuristic to determine if problem-specific heuristics perform better than generally good ones. A new adaptation of CPRU that adapts the research utilisation score by calculating the fraction used based on the amount of resources available given scheduled activities instead of looking at the resources of the problem instance. From the results, we concluded that CPRU may perform better for large instances of RCPSP- t compared to VSIDS in terms of generating good schedules within a few iterations. We also found that CPRU generates better schedules given a small time limit. We did not find evidence that the CPRU adaptation improved performance compared to CPRU in terms of schedule and time limits.