Sorry for the long text :D
PROBLEM:
imagine you are rescheduling activities for a deliverable which is running late:
first step would be to bring them all to the recently displayed week. afterwards you want to schedule them according to their interdependencies. that might lead to one or more of the activities will only start next week. so you jump to next week to also schedule those: you won't find the deliverable any more because after the reload the list is sorted anew... of course you could ignore the ones which should be done next week, but now they are scheduled for this week and people will find them in their app.
IDEA:
offer some way for people to schedule activities with specific dates (kind of like what we have on the progress page)