Officially there are two types of raids, one with 8 players and another called Alliance raids with 24 players. Although the alliance ones could be completed in under half an hour or less than that, but I do remember Dun Scaith definitely reaching the time limit when it first came out and players were wiping like nobodies business. But yep, just like Pence said the challenge lies with the 8 man content more than anything, esp Savage.