Bosses with long invulnerability phases

Exhibit A: Rugosa (the singing mermaid). If you don't do enough dps to kill this boss in a few seconds, she can do two (or three?) invulnerability phases when she jumps in the pool and sings her song FOR A FREAKING 1 MINUTE at a time!! That's a massive waste of the player's time!

Exhibit B: The first boss from Act 4 cultist island (and his map versions). It you don't kill him quickly enough, he gets 3 shiny buffs that make him invulnerable for a VERY long time. Something like 3-5 minutes! That's just insane!

Exhibit C: A boss from some Act 2 themed maps that looks like Jamanra wearing black clothes. This one periodically flies up in the air and becomes invulnerable while spawning adds or doing something else that doesn't seem to matter. But he can fly for 20-30 sec at a time. Not quite as bad as the other two but still an annoying waste of time.

Exhibit D: The final boss of Act 4 and Jade Isle. After you defeat his first two forms he goes into an extremely long animated sequence while invulnerable: blah blah blah Tukohama blah blah blah Power blah blah blah blah - before starting the final phase of the encounter.

Please make all those invulnerable phases shorter! And I mean a WHOLE LOT shorter.