No thats... err maybe I explained it in a wrong way....
What I meant is that it doesnt really matter which girls you use or in your team. Rather I was talking about the order in which the girls are placed into each of teams.
What I am trying to convey is that in a team (any of the teams) its better to put the AOE girls up front > meaning, on the first two/3 (from left to right, in case of your Signature the #1 is Alpinia, #2 is Winter Rose, #3 is.... etc) positions in your team, and put the single target hitters on the last place in the team. You dont have to change any of the girl, neither does it matter if you have any particullar girl in there for a certain purpose - like debuffing. All buffs/debuffs are applied instantly at the beginning of the combat, regardless of the order in which the girls are placed in the particular team itself. So you are not loosing out on anything.
The setup is used to minimize damage loss per battle, thus allowing you to finish the battle sooner and moving on to the next one.