They don't do weekly maintenance but they do maintenance fairly frequently. I'd guess the longest they've gone without doing at least one maintenance is one month and that might be stretching it. It's almost always on Monday nights starting at around 10 or 11 PM Pacific Time and ending around 1 AM Tuesday morning Pacific time (the reset for most weekly quest timers). They also implement fairly large patches ever 3-4 months with minor patches coming in almost every month. All of those require a maintenance and then possibly an additional maintenance to fix things.