I agree with this view. If there is no minimum holding period or a very short period that you are comfortable with, buy as much as you can afford and sell immediately for a quick profit.
With a holding period, you are now speculating that the price won’t drop more than the discount. I was very disappointed when my company added a 1 year holding period, but it is a large, stable company with minimal volatility, so I’m continuing to participate.
Holding beyond that, you need to evaluate it as an investment outside your work relationship. Based on what you know as an investor, would you buy and hold shares? What % of your portfolio would you allocate to a single investment? I recall a lot of employees were wiped out when Enron and Worldcom went out of business. They both seemed like great companies until everyone found out about their fraudulent financial statements.