There are two general times that repeatable activities reset, one daily and one weekly. There's also two common exceptions to the daily reset.
The game has three time options on the in-game clock display: the game client's Local Time or LT, Eorzean Time or ET, and Server Time or ST. Server time for all servers globally is the same as the GMT/BST time zones, and therefore does change for daylight savings.
The resets themselves do not move for daylight savings, and so they occur at different Server Times depending on the part of the year. All times below are Standard, non-Daylight Savings times.
The daily reset is 3PM GMT. This is 10AM Eastern, 9AM Central, 8AM Mountain, and 7AM Pacific.
There are two common exceptions to the Daily Reset: Grand Company Supply and Provision Missions and Levequest Allowances.
Supply and Provision Missions
The GC reset is 8PM GMT. This is 3PM Eastern, 2PM Central, 1PM Mountain, 12PM Pacific.
The leve reset is 12AM/PM GMT. This is 7AM/PM Eastern, 6AM/PM Central, 5AM/PM Mountain, and 4AM/PM Pacific.
The weekly reset is 8AM GMT on Tuesdays. This is 3AM Eastern, 2AM Central, 1AM Mountain, 12AM Pacific.
- ↑ More info is needed on which jurisdiction's daylight savings dates are used for Server Time. Is it client based?
- ↑ So any idea why server time is not actually server time? (Reddit)