You don’t need to grab an IP list for every channel you want to join, just one for regular chat and one for event chat. If you grab the IP list for a channel in event chat, the server list it responds with will work for every channel that’s on event chat; and same for regular channels.
The best suggestion I’ve seen on these boards is to just use 1 channel to look up each, which never changes it’s type:
https://api.twitch.tv/api/channels/riotgames/chat_properties (event chat cluster)
https://api.twitch.tv/api/channels/night/chat_properties (main chat cluster)
Though the last time they changed the server IPs, I saw an announcement on this bobard before hand; so if you decided to just hardcode the list it wouldn’t hurt you, you’d just need to be aware of it.
And of course if your app will be connecting to channels on an individual basis, querying their “chat_servers” is certainly a robust way to do it, all depends on how you want it to work.