So.. Why do you need 6 hours for this? It must be something big. They never have this long maintenance for a patch, or even for a regular maintenance. Atleast not that i can remember.
Why so long? The first things that come to min is fixing skill lag in WvW by upgrading servers, or removing PvE culling.
TL;DR: Lots of scripts that require exclusive access to enable safe changing of a lot of internal values inside our accounts make the game have to be shut down to be ready for the next patch.
