Instead of complaining I like to provide some constructive feedback and some possible considerations.
The 1 day notice can be tricky for new players but at the same time, new players are rarely equipped to complete the events anyway. I know from experience that by the time I was ready to prepare for any event, I'd figured out the basics and learnt to save and wait.
My only request, would be to perhaps increase this notice for events that overlap and have something connecting them such as the double chance and summoning event. People get excited at the start of an event and all reasoning goes out of the window. This is the perfect time to remind them that something else is on the horizon. OR better still, start them at the same time and completely avoid all this fuss :)
Obviously, if this is all some marketing ploy to get players to save and spend shard on the summoning event, then, buy more shards solely for the double chance... then, not much else to be said, its just how the world works. I'll still play the game, I enjoy it :)
Regards,