What material can be used to cover gaps between planks that are up to 150mm wide?

Using structural plywood to cover gaps between planks that are up to 150mm wide is a practical choice because structural plywood is designed to withstand significant loads and resist warping, making it suitable for outdoor or exposed conditions. Its strength and stability allow it to effectively bridge larger gaps in a scaffolding system, ensuring safety and durability. Additionally, the continuous and rigid surface of the plywood can help maintain a level working platform, reducing the risk of tripping or instability that could arise from unfilled gaps.

While other materials like wooden boards or plastic sheeting could potentially be used, they may not provide the same level of structural integrity or may not adequately fill the space without the risk of deformation or damage over time. Metal panels, although strong, may be less practical in terms of installation or flexibility in dealing with gaps, particularly given the dimensions specified in the question.