I wonder if there are a specific number of flashes in the islands time line. Eloise talks about there being pockets of energy all over the globe, suppose the flashes are similar in the sense that they are connected as the pockets are connected over the globe, only over time.
I thought of this while recently watching The Little Prince. The part where the crew finds the Outrigger boats and see that there is an Ajira water bottle in one. This clearly means that the gang has flashed to 2007, yet we don't know specifically where they are in 2007. It has to be after 316 landed, but is it before or after the 'incident' gang flashed back?
From what we gather, we can assume that the series of flashes happens in a predestined way, not just whenever the island decides to shoot the sky.
Think back when Desmond turned the fail safe and created the flash in the sky. Did he create another entry point into the line of time along some sort of flash cycle?
In This Place is Death the gang flashes 3/4 dozen times and most of those flashes are undetermined, but I would guess that at least one of them coordinated with the flash released by Desmond turning the key. What I think is that each flash represents a moment in time when someone released the energy... 'time travelers' are inside the cycle, moving rapidly from one space to the next in the order that they were released. Perhaps the flash that sent the Outrigger crew out of 2007 is the same flash that would carry the Incident crew back into 2007... if that were the case then one could have possibly mapped out the flashes, as if they were coordinates on a spatial globe of time.
In this case scenario the pre destined number of flashes that carry the losties through time, would have been increased by one when Desmond turned the key, (or in the case of the button, increased by one every 108 minutes once the computer was permanetly broken) creating significant holes into the space between the order of events... and less space between flashes...