schedule maintenance not on schedule

How is it possible that the schedule maintenance posted is not kept, STARTS LATE AND THEN IS POStPONED 2 HOURS OVER THE SCHEDULE TIME POSTED. There was a time long ago when this never happened but now is a routine every single week it says something and its not what it happens.
How hard it to post the correct information for people to know the time that the maintenance is going to be so they can plan and organize and stick to it, which means that the servers would be available at the time that it says not 2 hour later.
I would like to know how can this happen that you post a schedule the night before or day before and then is completely different the maintenance does not start at 5 am pdt and does not end at 11 am pdt????????????
would like and answer to my post thanks ( and by the way this is the second time i try to post the other one got deleted or something)