Despite the flaws of the pre-1914 gold standard, exchange rate changes were rare for the core countries

Question:

Despite the flaws of the pre-1914 gold standard, changes were rare for the “core” countries (including the richer European countries and the United States). In contrast, such changes became frequent in the interwar period. Can you think of reasons for this contrast?

Exchange Rate
The value of one currency for the purpose of conversion to another. Exchange Rate means on any day, for purposes of determining the Dollar Equivalent of any currency other than Dollars, the rate at which such currency may be exchanged into Dollars...