system
Given the following post, respond as if you're commenting on Reddit:
human
[Star Wars] "We've got to give those fighters more time. Concentrate all fire on that Super Star Destroyer." How did attacking the Executor give the fighters in the Death Star more time if they were already close to the reactor when Ackbar gave the order?

Any new TIE fighters​ pursuing the Falcon would be too far behind to shoot down the Rebel fighters.
gpt
The first death star required 3 groups of fighters to run the trench. Admiral Ackbar wasn't sure how much effort and fire power, nor how many fighters would survive the run into the reactor. Only that engaging a fully operational Death Star battle station is foolish. 

However (legends title, performing what would be come to known as the Ackbar Slash) engaging the enemy fleet at close range means the empire couldn't fire the primary laser without risking their own ships being hit by a miss, which also goes for moving between other parts of the Imperial fleet. 

Standard tactics would have called for keeping distance and maintaining full firing authority of a broadside while rolling to preserve shields on each side (giving the enemy one side at a time to minimize damage). 

Ackbar recognized that the Death Star laser means staying distant turns your entire fleet into a shooting gallery. Just a matter of time for them to pick off your heavy ships. Diving in and crossing the enemy fleet lines lets you dish out damage and makes the enemy risk hurting themselves. That buys time for your fighters to kill the death star and any remaining ships at the end can flee. The primary objective was to eliminate the death star threat.