In EBS workload demand plays an important role in getting the most out of your General Purpose (SSD) and Provisioned IOPS (SSD) volumes. In order for your volumes to deliver the amount of IOPS that are available, they need to have enough I/O requests sent to them. There is a relationship between the demand on the volumes, the amount of IOPS that are available to them, and the latency of the request (the amount of time it takes for the I/O operation to complete).
Latency is the true end-to-end client time of an I/O operation; in other words, when the client sends a IO, how long does it take to get an acknowledgement from the storage subsystem that the IO read or write is complete.
If your I/O latency is higher than you require, check your average queue length to make sure that your application is not trying to drive more IOPS than you have provisioned. You can maintain high IOPS while keeping latency down by maintaining a low average queue length (which is achieved by provisioning more IOPS for your volume).
Reference: http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/ebs-workload-demand.html

Explanation
- Scheduled scaling is the solution here, while "using the least amount of settings possible" - Beanstalk vs moving to ECS - ECS requires MORE CONFIGURATION / SETTINGS (task and service definitions, configuring ECS container agent) than Beanstalk (upload application code)
https://docs.aws.amazon.com/elasticbeanstalk/latest/dg/environments-cfg-autoscaling-scheduledactions.html Elastic Beanstalk supports time based scaling, since we are aware that the application performance slows down during the lunch hours.
https://aws.amazon.com/about-aws/whats-new/2015/05/aws-elastic-beanstalk-supports-time-based-scaling/

An elastic network interface (ENI) is defined as a virtual network interface that you can attach to an instance in a VPC and can include one public IP address, which can be auto-assigned to the elastic network interface for eth0 when you launch an instance, but only when you create an elastic network interface for eth0 instead of using an existing network interface.
Reference:
http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/using-eni.html