Why does greater flexibility of prices as time passes cause economists to utilize different macroeconomic models for different time horizons?

The different models provide economists with a better understanding of how different government policies in the short term affect the economy, when prices are inflexible verses over time, and prices are flexible.

Price stickiness moderates over time, meaning it is important for economists to develop separate economic models at different times. In some models, for example, the instances in which prices are highly inflexible are reflected, which is apparent immediately. There are also other models that reflect the long-term high degree of price flexibility.