Quests like the seasonal quests are usually done in the interim of working on other content, more important and are basically filler. But what you fail to account for in your estimation of effort is a critical thing - every step is easy for one person's work, but this isn't one person's work. Each of steps is worked on by different people in different departments. Now add all the time of stuff being shared back and forth over multiple days to coordinate, idea being settled and confirmed by leads, even smallest errors taking time to fix due to need to go back and forth yet again, etc etc. Ironically, when it comes to incredibly small things, corporate development team structure is a lot slower than solo indie devs at doing it, purely because of separation of duties and paper trails. So yeah, the amount of work going into it? Less than a week, definitely. The amount of time it takes between each step as things get coordinated? Definitely adds up to just as much if not more time.