In my opinion advents are little better than raid events. You can use thousands event tickets and just by very bad luck not get that one copy from event gacha to max limit break weapon/eidolon. Besides raid events are more grindy.
On advents it is best to focus on one thing (eidolon or weapon) and don't forget to get those daily half elixirs.
Here is yatagarasu ultimate, ability auto battle: