I don't find any of the dungeons really that 'difficult'. As a tank and brand new to it I tend to do 1-2 packs just because I don't know my way around, or when there's a wall, and whether or not I actually can handle all of them; but even at that pace I've cleared the new dungeons in maybe a little more than 30min or maybe even less, depending on if boss mechanics got us or not. Trash hasn't been an issue thus far, and I just hit 78.