I don't think (until they codify some sort of theater law) that you will ever find a one size fits all answer to everything...  You just go through life, picking and choosing those things that work and or appeal to you... (and hopefully, your audience.)

Amen.

I'm one for curtain calls being out of character, but you can't ever use a blanket policy for curtain calls.   Sometimes an out of character curtain call will completely break the audience's psyche.  I'll explain, don't worry.

In college, we did Zastrossi, Master of Discipline The show is extremely dark, and in the end, everyone dies but the villain.  Our scene changes were done by stage crew dressed in monks robes, and during a 'blue out' so the audience could see the actor, who just had the life beat out of him, get up and walk off.  This was done to alleviate the oppression of the show. In the final scene, every single character is killed, onstage, and each in a brutal manor.  They had blood all over them. Our curtain call had the stage hands come on, take a bow (since they were seen, and therefore kinda like characters), then they went to each of the actors and 'raised them from the dead' and they just stood there, with a blank stare on their face, illuminated by a strategically placed light. Black out.  Actors exit.

Now, put yourself in the audience's place.  how would you have felt if this person you had just seen stabbed to death got up with blood streaming down his face and started smiling and bowing as if nothing had ever happened?   would have ruined it for me.

THis show, btw, was the pres of the university's favorite show that the theater department had ever done.