I think most people can agree that a Mercy who never rezzes in order to chase a POTG rez, or one who poorly positions herself and dies at the beginning of every fight is not good. However, are there situations in which it's smarter to hold onto rez? There are some cases where rezzing is rather obvious, such as:

• Teamfight is still going on and 3 team members down
• Enemy team has burned through ults and your team has advantage
• A teammate has ult and asks for it
• Enemy Mercy is down/has already used rez

1-2 man rezzing has the potential to be more impactful than the larger rezzes, but what if the enemy team has ult advantage? What if they also have a Mercy? Is it wise to use rez to bait out enemy ults, since it is relatively easy to get another one? Would this change if you were playing attack or defense? In what situations would you hold back from rezzing?

I'd love to hear your opinions on the matter.