ETT Size?

Paramedic here. Have had this question in my head for years. On every field intubation for adults I've performed has been a 7.0. But we carry up to 8.5s and when I did my hospital clinicals years ago they had a 10.0 in the drawer. In what scenario are these being placed? It just seems so large and unnecessary especially a 10.0 for any except a very rare scenario