I'm Doing [activity] Join If You Can!
Problem: I like to do things with people but there is a high overhead in thinking about who might be free and reaching out to them individually to invite them.
Solution: Contact lists plus a Siri shortcut to blast out a message to those people that lets people know I'm going to be doing something and they can join if they are free. Why doesn't a group chat solve this? Well you can't easily add/remove people in a group chat without creating a new group chat. Then you devolve into group chat hell in which you have a unique chat for each combination of your friends 😱.
The Siri shortcut is called "Bat Signal". The idea is to give people a quick update on what I'm doing (usually within a few hours) so they can join if it happens to work out.
Main drawback is that it bumps up each person in my Messages history. Also it can be spammy to people who only want to join occasionally.