That's actually incorrect, it's more complicated than that.
In general you should not make events that depend on this, because you end up running down the rabbit hole of internal engine details, and if you rely on it your events will be hard to understand, break easily if changed, and possibly break if internal engine details change in future.
But if you really want to know how it works, just make a test project that has some events and see what order the events run in, like this: https://www.dropbox.com/s/kr4kilz4rxx4s8s/include-sequencing.c3p?dl=0
As this project demonstrates, triggers actually run in most-nested event sheet to least-nested, whereas normal events run at the point the include is reached when running events, producing a nested ordering depending on whether the events precede or follow the include.
As I said... it's probably unwise to use this though.