Normally I sell all my ESPP stock as quick as possible. Several years ago my company did not have a mandatory holding period, so I always sold it immediately. I had to pay a higher tax rate on the 15% discount, but it was a guaranteed return with no risk.
Now we have a one year required holding period, which is great for lowering taxes, but adds volatility risk. Last year our stock started the year overpriced, then dropped below what I considered a fair price. I stopped selling stock at that point to hold for a fair price. We're just now getting close to a reasonable price, but now I'm holding way too much company stock (I've kept buying my maximum along the way). I'm slowly starting to sell and hope to get back to my old practice of always selling by the end of the year.
On the bright side, I've added a little extra income along the way by selling covered calls against the shares I'm holding. In the last year I've made more from that than dividends on the same shares and have offset the loss on the shares I bought at the peak of the 2022 market. I would still rather sell without a holding period though.