You will be surprise, but not every Map is that easy. Of course i use a Level 30 Team (without AW). So far as i tried Map 4 but its very hard to get the 3 Star due to the high damage the 3 Valkyrie enemys at the end of this Map (i can kill all 3 Valkyrie but not everyone will survive). I gave up later

The other Maps (5-7) are much much easier then the Maps 1-4. But overall if you have a Team between Level 50 and 70 then you should be fine.
Map 4 is the only Map i didnt get the 3 Star so far. Yes, of course i can level up all my Team Member but i like the challenge so beat as many Maps as possible with an Level 30 Team.