What is the average volume a stock should be at to expect reasonable liquidity?
That would depend on the stock price. A penny stock ($5 and under) I’d say an average of over 500,000-1 million shares a day or more. Stock prices above that you could go a bit lower, but personally I don’t trade stocks under 100,000 average daily volume just for liquidity purposes. Make sure it’s an average volume also, not just a trading day anomaly.