When Stephen R. Blank left investment banking in the late 1990s to the become a senior resident fellow at the Urban Land Institute, he brought with him his expertise in and his respect for real estate finance, but he also brought his impatience. In a recent frank conversation with BNA’s Richard Cowden, Blank airs concerns about what he considers a tendency in the real estate sector to disregard warning signs when the economy and property fundamentals begin to soften. Here he offers some candid views on policies designed to curb excessive risk and on the industry’s reluctance to ‘‘get rich slow.’’