I personally really enjoy it to some extent. I usually can't clear the event shop in my second account, but now I can easily clear the event shop in my second and third account except for Monuments.
Since the events is also quite long, I'm feel a bit relaxed and can enjoy do other things rather than focusing to farm here. As long as you have something else to do other than playing FGO, imo 3 weeks event is a good thing. Of course, that's also depends on the event itself (Grail Front for example is best only for one week).