Hello! I think you're right, a few times a month is not enough. Of course a lot depends on your activity, but you still need to stay in touch. We use messenger for this purpose, there are many of them today, you need to choose the most comfortable one for you, then your employees can at any moment clarify something about work or just find out how someone is doing. There are many articles with tips on how to organize work with colleagues and with clients if you work remotely, I liked this one https://www.helpwire.app/blog/how-to-build-remote-support-team/