I use Slack every day. It's my go-to method of communication with clients.
For those clients that don't bother with Slack (or a similar tool), I find communication has become tedious and inefficient. That's only part of the reason why Slack has become so important for teams, organizations, and even families all over the globe.
Also: How (and why) to use Slack Connect
Slack is not only efficient, but it's also flexible. You can use the app for years and find there are helpful features that have slipped past your purview.
One such feature is called Saved items and it's exactly what you think it is