Occasionally I have a plan for publishing multiple papers that are related to a project. Whether due to the actual order of experiments (and therefore data availability), a plan to set up a cascading story or to get the "important" one out first before cleaning up the little details..there is a plan. (you "complete story" folks can stop reading now)
Do you do that? Maybe it is just me.
Anyway, the process of review has a way of screwing with these grand plans. Especially if you send out more than one at a time. Something gets stalled going to a third journal, something flies in even faster than you hoped....next thing you know your order is all screwed up.