Some events have resets part-way through their week-long duration.
As an example, look no further than the week-long Conqueror event where, on initial release, and having completed all of the available tasks, you will only have earned 34 of the possible 44 event center points. You have to wait for the reset that occurs part-way through the event’s week-long duration so that some of the tasks become available again, and complete them again, in order to get the remaining 10 event center points, i.e. completing 100% of the tasks does not give you 100% of the event center points. You have to do more than 100% of the tasks.
I reported this back in May…
This isn’t the only event that does this. Quite a few of them reset part-way through their durations, most of them on different days to each other.