Is it important to always have an ec2 instance in each zone of your load balancer? Are there advantages to having more than two or three zones?
We set up our application in an EC2 AutoScaling Group serving as the single Target Group of an Application Load Balancer. For our initial deployment, we set both the Launch Template and the Load Balancer to use six Availability zones. Based on the recommendation in paragraph 4 here, we set the AutoScaling Group's minimum size to six so there'd always be at least one box in each Zone.
In practice, most of the time we don't need six boxes; a minimum pool of two or three would give us the redundancy we need.
I can understand that without Cross-Zone Load Balancing it would be important to have a box in each zone, but Application Load Balancers always use Cross-Zone Load Balancing, so it seems like it shouldn't matter.
From the other angle, are there pros or cons to having our LB in so many zones?