There's a related issue here that I haven't heard come up. At the moment, we often see people just wait until the active player tries to move on before playing their action. In essence, they're saying, "I want to play this card at the end of the phase." However, the rules, as I understand them, don't accomodate that sentiment.
Let's say it's your deployment phase. Your opponent wants to play some event at the end of your deployment phase, say Force Choke to combo with Darth Vader. You play a unit as an action, let's say Twi'lek Loyalist. It's now your opponent's turn to play an action. He chooses to pass since there's only 1 hp on the table, and he'd like to deal maximum damage if he can. He chooses to pass. Now you choose to pass instead of play more units. Suddenly, the action window has closed because both players have passed consecutively. Your opponent now has to wait for the next action window.
In other words, a player can't wait until his/her opponent is done before playing X because they would have to pass until the opponent if finished and when the opponent finishes by passing, two consecutive passes have occurred, closing the action window (pg 24 of core rules).
At the moment, this timing is seemingly trivial, but I think it could potentially have ramifications later on.