IMO, because of war and tournament VF rule, at least 3x mana on level 11, so we need 2x more mana troop at lvl 11. So we can use for 3-2 on offense, best setup 3-2 for VF rule IMO.
But for me, even without VF rule, I was plan step by step minimum 3x mana troop:
5,5,11 and next 11,11,17, and next 11,11,23.
lvl5: is great for VF + class, and costume
lvl11: for VF or avarage + class20
lvl17: for avarage + class
lvl23: for avarage
etc…
After that, I would level ninja troop for sniper or high attack stat heroes.