I wouldn't do it for 5% off the price on the last day.
We get some percent off whatever is lower: the price on the first or last day. So you are more guaranteed to get a good price. And you can also pull your money out and forgo the purchase up to about a week before the end of the period, if the stock price is doing something weird. I believe we get either 10 or 15% off, whatever it was we decided it was worth it.
We do sell almost* immediately. We just don't want further exposure to the company that provides 100% of our household income. So we pay a higher tax rate on the profit, but we still make plenty of profit. Over time as investments grow and HHI is a smaller chunk of our net worth, we may try to hold it for longer.
*Almost because there is a clear seasonal pattern to the stock, for the past 5-10 years at least, so we "time the market" by saving the December stock until spring to sell, so still not long enough to get the lower capital gains rate. We sell the June stock immediately.