Maintenances are scheduled based on Team availability, commonly we need few members for that.
We are also trying to deliver newly developed content as soon as possible.
We are also trying to not choose hours with peak amounts of players online, but it's not always possible.
None of the last 10 maintenances happened on Saturday evening.
Most of the regular maintenances takes 10-30 min, only bigger content takes few hours.
Datacenter maintenances timeframes do not depend on PlayerNet.
~8 hours one, even if we can control timeframes, would interrupt someone play time.