I'm currently struggling with this question too.
Right now, I own 7.4% of my investment portfolio as two company stocks, all acquired via 401(k) match. I'm holding onto them because they were "free", and my current employer's stock has actually been going gangbusters in recent years. But this is small fry compared to my unexercised stock options, which comprise a whopping 42% of my portfolio at current market value. This would make my hair stand on end if I actually sunk my own money in, but I haven't. I just try to manage my expectations and exuberance when I check my NW, because... yeah. A meteor can flatten my employer tomorrow.
It makes sense to ditch most (if not all) of one's company stock at FIRE, because the risk/volatility probably isn't worth it. But I'll admit to having a slight bit of fun when the stock price does soar. I'm just hoping that it can hold on until I'm ready to FIRE and cash out.