You balance only if the EICAS message comes on, otherwise you don't. The only real interesting situation regarding fuel balancing arises when your tank quantities become unreliable. This happened to me some time ago when I had 6 tanks with densitometer failures driving the fuel management card crazy. On that situation, we used the calculated fuel figure and made up our own fuel used chart (F/F x time) to figure out how much we had left in all the different tanks. When the fuel imbalance message came up, we relied on the ACMS flight control display on the lower display to make sure the balancing was really working. Kept us realy awake on the 14 hour sector!
