Individual markets are very specific in their behavior, so it is surprising how traders generalized one behavior for different markets. It is not only about biases like trending or ranging markets, but also impact of news on price and market.
We can listen many times that you should not have opened positions overnight. This can be understand on Futures or Equity markets, where you cannot manipulate with positions due to closed markets and possible gaps could be dangerous for you. But for Forex market with trading on spot without interruption, it is not important for retail traders at all. Of course, liquidity is lower in these trading hours, but retail positions are not in danger. What is relevant for Forex market? For example weekend interruptions. On Forex you can trade 24/5 and weekend is possibly dangerous period. Many times, some important elections or decisions have been made during the weekend which led to price gaps on Sunday open.