My airline (Qantas) operates a mixture of 4 door (+ overwing exits) and 8 door (ex BA) B767 models. Min cabin crew on the 4 door is 7 crew and on the 8 door is 8 crew. Being the tight-arsed company that it is, we almost always operate with minimum crew.
We also have a couple of high(ish) density configured 4 door aircraft where 2 seats have to blocked out to meet the 1 crew/36 pax requirement in Australia when operating with 7 crew. (OK 254 pax is a bit woosie compared to First Choices' 312!)
Oh and did I mention - a full, hot meal service between Melbourne & Sydney, which can be as little as a 43 minute sector.
I guess rules vary from country to country . . .