Formations can change during the match:
5-3-2 to 3-5-2
4-4-2 to 4-5-1 (4-2-3-1)
4-3-3 to 4-5-1 (4-2-3-1)
3-4-3 to 3-6-1
I don't think it's about the formation but more about the capability of a coach to field the right players to make his tactics work. At the end, most formations can be a success or a failure.
Personally, I have nothing against any formation as long as it's used considering the players' abilities (Lippi talk).