Winches deserve respect.
I've been on winches where a pawl stuck 3 times. All related to using grease on the pawls (don't do that). Only one was my boat. There were no injuries or excitement.
All three where completely obvious by feel and did NOT result in the handle spinning. I could feel there was no catch, added a turn, and cross sheeted. In all three cases I later popped the top of the winch, either while underway or at the dock that afternoon, wiped off the pawl and gave it a few drops of motor oil, and that was the end of it.
The likelihood of the winch spinning when not been used seems vanishingly small. I have never heard of spontaneous release. I've never heard of a cleated tail becoming loaded because of this. I have seen tails with a good load on them when the winch did not have enough turns and the wind increased. Totally unrelated, and would not cause the handle to turn, but worthy of caution. Often you remove the handle when easing the line, but not if you are trimming from time to time and may grind a few inches in soon. I've seen damaged gears, but the winches were horribly maintained, so this should not have been a surprise.
If you are cranking the winch, use a firm grip, always in control. No crazy spinning and no throwing your weight at it. Control. And don't use grease on the pawls, and replace the springs.
[I was sailing a few weeks ago, found a pawl spring on the deck underway, and then found myself checking the winches (4) one at a time, underway, because of a nagging doubt that a spring was missing. In fact, it must have been one I replaced but failed to discard. No harm.]