As a guide:
For undergraduate study 1 point = 10 hours (except in many Health Sciences papers), e.g. the expected student workload is 180 hours for a 18-point paper, 240 hours for an 24-point paper, and 360 hours for a 36-point paper.
For postgraduate study 1 point = 12 hours (except in Health Sciences), e.g. expected student workload is 240 hours for a 20-point paper.