If you’re unfamiliar with the tool, it’s essentially meant for players to give CCP a heads up of impending large scale fights which may cause some serious stress on the server. This stress will lead to performance issues, which no one likes.
The team goes on to explain how certain systems can be effected,
“A very busy system like Jita pretty much has an entire node to itself since it constantly has a large volume of players in local and a very busy market. On the other hand, a quiet system in the far outer reaches of Omist or a dead-end lowsec system somewhere in Solitude might be placed on a different node which it shares with many other similarly quiet systems that see very little traffic on a typical day.”
If you want to use the tool, you may want to take a look at CCP’s recommendations before submitting. It looks like only a corporation CEO or Director is allowed to submit such a notification to CCP. Additionally, CCP requests as much advance notice as possible before submitting.
To that end, accuracy and timeliness are rather important, as stressed by CCP,
“Please be as conservative and accurate as possible when entering the coverage time into the form. If you're expecting a big fight over a timer but it doesn't come out until 02:00 UTC you don't need to request reinforcement for the entire day. We also can’t take “reservations” on a node to reinforce a given system for an extended period of time.”