I think it should be like the Automation Tower where it resets every 2 weeks. But I could live with it being like Labyrinth Hell Raid and being reset once a month. 

The odds of either the above happening though... 

It will be interesting to see how much work has been done on the floor bosses since the last AI event, and if they will be different from each other this time. Going to be a tad bit disappointed if they are all  carbon copies of the earlier AI event though. 

That would be super cool, but it's technicaly impossible cause you would need to have both players playing at the same time if they want to fight.

A few reasons why not: 

Economy and rewards flow balancing - the same reason why you can do Hell Raid only once a month to get your hands on LVL88 gear and possibly galaxy bms.

Also, not every E7 player got a ton of free time to play the game - families, responsibilities, jobs, etc.- and mobile games are usually a filler activity in between. Stacking too many events will overwhelm people feeling like they are constantly missing out or behind which will lead to frustration. 

RHammerThis time between events is fine in my opinion.

Imagine the same gear but for damage dealers instead of tanks/healers