If you want to use Rule Machine and want repeated notifications, I'd start by looking at the examples in this thread to see if any are helpful for your case:
If you don't want repeats, you can ignore most of the complexity in those examples, and I think the suggestion above (local variable, private boolean, etc.) would be one way to handle what you want.
In other cases, you might be able to use the built-in Notifications app, but that can really only handle one device (one attribute, really), so you'll probably need a rule to get what you want.