This thread reminds me of an incident that occurred many years ago when I was flying a very new three-axis microlight on a cold day.
After flying for about 30 minutes, I noticed that the throttle was jammed at cruise revs. No problem, I thought- I will simply fly back to above the airfield and switch off the mags and glide to a landing. However, when I tried this, one of the mag switches literally disintegrated leaving the engine running on one mag. Still not a problem, I thought- I will switch off the fuel and glide to a landing. This was when I discovered how long the engine would run after switching off the fuel, particularly at lowish revs. It ran so long (even though my passenger/student was applying full choke) that I overran the main landing area and touched down in a rough area, collapsing the nose-wheel, fortunately with no injuries. It turned out the throttle Bowden cable had some moisture in it and had frozen.
I have always made a point since of running the engine in each aircraft I have owned at idle revs on the ground with the fuel switched off to see how long it will keep going- it is usually 1-2 mins. Incidentally, it is a top tip (by Bob Grimstead, I think) to switch the fuel off before you try to hand start solo. You normally have more than enough time to walk round and switch the fuel on again and if it does start up too fast and jump the chocks then at least it will not get too far! (Although this will not happen either if you apply his other top tip- tie the tail-wheel to something really solid with a link you can release from the cockpit).