Most economists see the assumption of "continuous" market clearing as not very realistic. However, many see the assumption of flexible prices as useful in long-run analysis, since prices are not stuck forever: market-clearing models describe the equilibrium towards which the economy gravitates. Therefore, many macroeconomists feel that price flexibility is a good assumption for studying long-run issues, such as growth in real GDP. Other economists argue that price adjustment may take so much time that the process of equilibration may change the underlying conditions that determine long-run equilibrium. That is, there may be path dependence, as when a long depression changes the nature of the "full employment" period that follows.