11 Years in Fire/EMS, I can only recall 2. One t-bone and one head on, considerable damage to vehicles, access to latch limited and seatbelt snared on various deformed debris. Both times cut lap and shoulder clear with shears. As I responded to a lot of minor MVAs, I guess it would be fair to say around 10 major wrecks a year requiring more than a door pop, so just at or less than 2% of the time for me.

Cut plenty of seatbelts in training, I was involved in my departments hydraulic rescue tool training and we'd end up cutting up 4 wrecks from the salvage yard every week in the summer. I found a lot of the hook bladed cutters would bind up on a slightly loose belt (even sharp ones) and need 2 hands to operate. A rounded tip serrated Spyderco rescue blade or shears allowed me to cut the belts quickly and safely with one hand.