As the lead official, you should mirror the ball as it swings from side to side and continually look for a reason to rotate to the ball side. Mirroring the ball in the lead allows you to maintain the best outside-in look and puts you in the best position to rotate if the play dictates.
Mirroring does not mean running back and forth unnecessarily.
When the ball moves to the weak side:
Closing down keeps you engaged in the play and prevents you from being late when rotation becomes necessary.
When a competitive matchup / post up is forming in the post, the lead should:
Too many lead officials stay wide when the ball swings to the weak side. When this happens, the center official is left to officiate the post play and the primary matchup alone.