Optimistic and Pessimistic Loadshedding

What was the context where these two words were used?

Typically load-shedding is either voluntary or involuntary, and depends upon the system conditions that cause the need and the utility's response. The utility can initiate the load shedding in response to short term controllable future demand (voluntary), or it can occur automatically as part of a forced load-shedding program built in to the operating procedures and/or protective relaying of the entire system (involuntary). You can see where optimistic and pessimistic fit.

You can also find "pessimistic" in this GE document on load shedding relays , just reverse the context to understand what "optimistic" means.