When your house has a low-pitch roof, as mine did, snow can build up more easily. When you have more than say, 18" on your roof, it's time to haul out the "snow rake" and pull as much off the edges as you can.
The primary reason is to prevent "ice dams" from forming. That's when the snow at the edge melts and refreezes... then when more snow melts, the water has nowhere to drain, but backs up, eventually draining into your house. But with the edges free, melting and draining occurs properly and faster.
I owned my little house for the 2018-2019 and 2019-2020 winters complete, but sold the house January 2021. I miss many things about it, but not the snow-raking.