1- Gets a check every tick. "Triggers" every tick. You can just put "8 directions is enabled" and it will be the same thing.
2- Gets a check every tick. But only triggers when a condition is met: every 0.3 seconds.
3- Gets a check every tick. But only triggers when the condition is met.
4- Black event/no condition: "Triggers" every tick.
Keep in mind that "on trigger" events also gets checked every tick.
If you have "on collision" for 100 object that means 100 collision checks every tick EVEN IF THEY ARE NOT COLLIDING. And the actions that follow will trigger once when there is a collision.
This was a problem for me in a game with hundred thousand+ entities (enemies,bullets) where i was wasting millions of unnecessary collision checks in things that didn't have a chance of ever colliding and for things that didn't even exist yet haha.
TLDR: The entire code gets check every tick, or at least the first event in nested events situations.
That's the way I understand it from the test I performed, If I'm wrong please let me know.