Does Purchasing Power Parity Apply to Real-World Forex Execution Timelines?

Why can currency pairs remain drastically overvalued or undervalued relative to Purchasing Power Parity for an entire decade without mean-reverting? Macroeconomic theory dictates that exchange rates should adjust so that identical baskets of goods cost the same in different countries. Yet, structural trade deficits, safe-haven capital flight, and geopolitical capital shifts keep currencies like USD or CHF trading far away from theoretical fair value for years. Is PPP an abstract academic exercise that carries zero practical value for short-term and medium-term traders?