Wait is thirsting killing the person while they are down? Or letting them bleed out?
What's so bad about killing someone when they are down? Waste of resources when you should focus on the other two in the squad, I'm assuming?
Situational, usually its better to let them be and try to kill the rest instead.
But if the downed guy can hide somewhere and someone could revive him, finish him if possible.
If they are midde of nothing or you know his friends not able to revive him and it doesnt matter if he pings your location for them 5 times per second then let him be.
Depends so much but usually I dont touch them, it can be just good trap to let some people try to revive to get easy kill.
Its very different in this compared to other BR:s because even if you finish someone they can be revived so finishing them asap doesnt really do anything if you cant finish the whole squad, so in that way you should not finish them.