Almost Ready... Missions

There is no worse cliche missions than one's that goike this.

You: Open that door.
NPC: Alright, but it's going to take a minute!
*Enemies Attack*
You: *pew pew*
NPC: *still opening door*
You: *pew pew*
*Enemies stop spawning*
NPC: *Almost done!*
*All enemies are dead*
NPC: Done!

Now the ones where you survive endless rounds until they actually do something are much much more fun and realistic. Die CoD