I do this on an ad hoc basis as I’m developing a rule but I tend to only do it for Channel triggered rules. And once it works I’ll often eliminate the test Item.
In all other cases, I’ll either change the state of Items through the Karaf console or the REST API docs to change or command Items to simulate events to trigger rules I want to test. This lets me avoid adding lots of new Items and adding lots of new controls to my sitemap.