Ugh, that sounds awful. I've maxed out at 4, but I only belong to Slack channels for customers that I work with. I had taken this as a huge plus in my circums

Ugh, that sounds awful. I've maxed out at 4, but I only belong to Slack channels for customers that I work with. I had taken this as a huge plus in my circumstances -- having them separated in their own space per organization allowed me to decide what set of rules I use for replying very quickly vs. when I get a Round Tuit, but that's a very small problem to fix if I had to manage credentials for 15 channels!