Chats are crazy good for instant/async conversations, they are really more efficient than email.
But when you start to dig the chat to find old messages, you are doing it wrong. Whenever there is an important information, move it to your knowledge base (documentation website, wiki, forum, you choose it.)
In the inspiration of keep or sweep it is also probably a good idea, mainly for privacy matter, to delete old messages.
For these 2 really good reasons, let me introduce you with a RocketChat feature you might have miss.
If you need help setting it up, don’t hesitate to comment here. Or contact us for private support!
I just set it up in our main chat. I’ll delete things older than a year and keep pinned messages.