Planning systems are generally divided into plan-led and development-led systems. However, it is quite common that the planning practice follows development-led planning although the planning system would structurally be plan-led. To study how development-led planning affects the implementation of large-scale urban development projects, we conducted a cross-sectional survey in Finland – a country with a hierarchical setting of legally binding zoning plans which can be prepared by following either plan-led or development-led practices. The survey respondents were civil servants managing implementation of large-scale urban development projects. Our results quite surprisingly suggest that development-led planning may cause the projects to become more vulnerable to property market uncertainty compared to the projects following the plan-led practises. These results challenge the usual output-based legitimation of development-led planning to some extent.