There are situations where you may choose to use design sections rather than design strips. This would include:

• In some areas, you may only require design information at one cross section rather than for an entire span.
• A design strip may not provide sufficient design information.
• A design strip may be inappropriate. For example, a slab step may not be orthogonal to the span (and design strip) and you want the reinforcement bars designed perpendicular to the step. In this case, you might draw a design section parallel to the step.
• You find it is too difficult to define a design strip for an area with very complicated structural geometry.