They Wouldn’t Be Missed
When a TV show loses an actor or actress, the writers have to replace their character with a new one and make sure it’s all consistent with the plot. This takes valuable time away from what could have otherwise been a kick-ass space battle.
I’d be too impatient to artfully work around a change in cast. I wonder if you could get away with doing a half-assed job of replacing the actor or actress but essentially keep the character the same. You could introduce the new character, make a lame attempt to flesh them out for that episode, then forget all that and write the new character just like the old one: same personality, same way of speaking, same past, knowledge, etc. You’d just pretend that nothing really happened and continue on. It’d be hilarious!