According to our investment principle, we don’t pay much attention to liquidity since it’s a concern of the stock market. If we have an opportunity to cheaply buy these companies, we can invest in them.
However, liquidity will become an issue in one case. If the size of our investment is too much larger than the stock’s liquidity, by the time we buy as many stocks as we want (such as 10%-20% of our portfolio), the average buying price will rise above the fair price or our margin of safety. That might prevent us from investing. We’ll need to look for companies that suit the size of our investment.
See Warren Buffett for example; his portfolio has grown so large that he can no longer invest in small companies. He must only buy stocks or companies with hundreds of millions in net profit, as opposed to when he was younger and could invest in a range of stocks.
So, the answer to the question above depends on the size of your portfolio. The larger it is, the higher the liquidity of the stock you want to buy should be.