The Henry George theorem, named for 19th century U.S. political economist and activist Henry George, states that under certain conditions, aggregate spending by government on public goods will increase aggregate rent based on land value (land rent) more than that amount, with the benefit of the last marginal investment equaling its cost. This general relationship, first noted by the French physiocrats in the 18th century, is one basis for advocating the collection of a tax based on land rents to help defray the cost of public investment that helps create land values. Henry George popularized this method of raising public revenue in his works (especially in Progress and Poverty), which launched the 'single tax' movement.
Obviously government can be very inefficient. Government can spend trillions of dollars building landfill or creating even bigger problems. So we would need at least some "benevolent" dictator and that's not reasonable "conditions".
So what's the conditions?