The most useless calendar widget is made by Apple. I constantly forget that someone’s birthday or something important is coming up later in the week.
Now I understand that you can set up alerts and you can set up reminders for stuff. I also understand that you can choose a different size widget. But depending on the size and the amount of events it’s possible it won’t even show you what’s going on the next day in the larger widget as well.
This is forced me to use third-party widgets to display calendar events for the week on my home screen. I hate it because I have no idea if it’s stealing my data.
Bonus Edit!
The large widget fails to show you what’s happening today!
You're just salty because you missed that one event at that one place with those specific people. Apple put it in your calendar, how is that not helpful!? /s
EDIT: I was making a dumb joke about how it didn't show you any details, even if it would take up the same space...