I had one case where I needed to store account data and ended up storing it in a gen server object for each account which pushed its state to all devices logged

I had one case where I needed to store account data and ended up storing it in a gen server object for each account which pushed its state to all devices logged into that account. It was so easy to build I forgot about it but this 4-hour project would have taken over a week if I had done it in any other language.