For events, Self-Switches A,B,C,D are your friend, in this regard. In the eventing pages, you can test for self-switch states; it just depends how you implement them.
Check out Redweaver's "Tutorial Town" video series on YouTube, and his Tutorial Town project in the Steam Workshop to download and examine; I've seen a few good event examples in that project where the self-switches are used to good effect. (For example, many of the townies in the starting village may have different things to say in a particular order, such as sending you on a so-called "FedEx quest" to deliver something; with the self-switches, the correct things are said in the correct order. Seriously; take a look -- that's why Redweaver shared it.)