Tons of times. You can tell this person was a greenhorn though, as they did not grab the shovel out of mid air as it was coming off the roof with the snow.
Seriously though. I have done a slightly different version. On the shop roof, which is metal. I have put a salamander in the attic space. Heated that up to get the snow to loosen its bond with the roof surface and then tossed a line from the front of the shop to the back, along the ridge line and pulled. The string cut through the snow similar to this, but in a vertical manner. That separated the two sides of the snow on the roof and the both slid at the same time.
-John