It's rare that I use rescue.
- When I use it on a DD, it's because the next mechanic absolutely will one-shot them, and their execution of other, easier earlier mechanics makes it clear they don't know that the next mechanic will one-shot them.
- When I use it on a tank, it's because the tank has placed the target somewhere that they will get 90% damage reduction or an extreme damage boost--tethered mob pairs, proximity chains, outside a crystal glow, etc--and they are parked there with no indication that they are going to move the target so that we don't have to work 10x as hard.
The players who need to be rescued don't understand that they need to be rescued. Therefore, they should not be allowed to disable being rescued.