Good points by @Mr_JDavey
Generally, Element Exists does not work well for waiting for elements to appear, but is useful to perform actions based on that element. You would need to put it inside a Do while (or Flow Chart loop) in order to use it as a wait machine which then also requires an exit to avoid infinite loops. I have recently used Element Exists to close all windows of a given selector, so it loops until the Element is no longer found.
The wait methods I use the most are with Retry Scope or Find Element
Find Element works well because the TimeoutMS let’s you wait until it shows up and fails if it never shows up. Then, you can also use the element variable to perform an action on it.
Retry Scope is useful, cause it can be used like a loop that has a built in exit (retry count). So you can try to click on a button but if it’s not available yet and gives you an exception, it will try again after a second.