Every formation
has to take an action, you cannot deliberately leave formations un-activated (this is to stop players not activating formations which with a failed activation roll could affect the outcome of the game).
Highlighted relevant part.
Quote:
1.6 THE ACTION PHASE
In the action phase, the players take it in turns to carry out actions with their unbroken formations. Each unbroken formation can take one action per turn. The player that won the strategy roll can choose whether to go first or second. The player going first then carries out an action with one formation, and then their opponent does likewise, and so on until all formations have taken an action. If one player runs out of formations to activate, then the opposing player may keep on activating formations one after the other until all of his formations have taken an action.
The Overwatch activation rule has a stipulation which allows formations , under certain circumstances, to not have to take an action (staying on overwatch).
The Overwatch rules allows formations to go on overwatch in a turn and remain on or use overwatch in the following turn (no roll needed to stay on overwatch into a following turn).
To take any action in the following turn would need an activation roll. Even to put a formation that is already on overwatch back onto overwatch would need a roll (often players will put formations back onto overwatch to delay using other formations too soon).
If a formation on overwatch hasn't been activated by the end of the turn (no other formations left to activate) then they are allowed to remain on overwatch as is stated in 1.10 (no roll needed, see FAQ)
From 1.10 Overwatch
Quote:
Formations remain on overwatch until they either shoot, or they undertake a new action in the following turn. Note that this means that a unit can go into overwatch on one turn, and not shoot until the following turn. Shooting in the following turn counts as your action for that turn, and will stop the formation taking an action later on. If the formation does not shoot in the following turn then it may take an action instead of shooting.
The FAQ
Quote:
Q: Can a unit remain on Overwatch into a following turn?
A: If the Formation hasn't fired by the end of the turn, then they can remain on Overwatch into the following turn.
The FAQ allows the formation to remain on overwatch (no activation roll needed) into the following turn as long as it hasn't fired in the previous turn wether it was put on overwatch in the previous turn or an even earlier turn (so no activation roll is needed to remain on overwatch from turn to turn).
