Volatility Expansion and Contraction

Volatility changes can affect option position. If I have many position open on the sell side and when volatility expand, many of the postilions will tested and triggered the stop loss or will be deep ITM when expires. However, when volatility contract, I can exit my positions with profit quickly or let it expires worthless. If we understand this principle; as seller of option, the preference is to sell when volatility is high.

For S&P Index,  I prefer to use VIX >20 and for Equity I target to sell when IVR >50%.