When a single stock rips, the vol catches a bid, and that's what makes rolling a winner awkward.
You bought the call, the stock's gone your way, the delta and the vol have both worked for you. Now you want to keep the view alive with a longer expiry.
The problem is you'd be buying that new option on a much higher vol than the one you originally paid. It happens in single stocks far more than it does in the index, where vol usually goes the other way on a rally.
So roll into a call spread instead of another outright. You're selling some of that expensive vol back, you keep leverage to the remaining premium, and what you give up is gamma and explosiveness.
That's a trade-off I'd take when something's already had a big run, I don't know when it stops, and I don't want to be out of it either. If they vol has repriced materially higher, lightening up on the VEGA makes sense.