What keeps a player from deliberately planning their own initiative action themselves by choosing to act in a predefined sequence and waiting until a monster has acted?
If all the players do this, they can arrange their actions to maximum effect vs creatures like, say Hydras, where the Hydra goes, then the Melee classes (to pop off heads) then the fire wielders, to cauterize before the Hydra's regeneration goes off.
This seems like an entirely valid strategy, especially for a party that has fought together for a long time and knows each others' fighting styles and abilities, but the Initiative rules assume every fight is a mad scramble to act first, even though this is not necessarily the optimal course of action.
So the question is: Can the players deliberately choose which order to act in at the onset of combat (not during combat, when there's too much going on to make such detailed plans), thus setting their own initiative using disciplined tactics?