Thing is, when there is no raid boss event going, and event maps spawn nearly no bosses, even if you do all the "refresh boss list" tricks, it can be barren for hours.

Thats why having a level 1 2* girl without affection bonuses is so popular among some people, cause you can 1 RB shot bosses for 200 dmg fast, so that you have a chance that boss you spawned wont die before you make your second attack .

Of course having allies who you talk with on discord on something to share bosses among each other with some kind of deal that you share boss and allies will just poke, and then you nuke him yourself after some time or some other strategy would help a lot.