I think the per-second billing is off the point. How does it help, if the EC2 instance takes tens of seconds to launch, and tens of seconds to bootstrap?
To make the most of per-second billing, the compute unit should be deployed within seconds, e.g. immutable. prebaked container. You launch containers on demand, and pay by seconds.
It has a one minute minimum anyway. And does it not help? Let's say a deployment strategy has a temporary increase in instances so it can transition to a new version of the application. If your deployment takes 5 minutes, you're only paying for 5 minutes worth of extra instances whereas the hourly billing would get you for an entire hour. Am I completely misunderstanding something?
To make the most of per-second billing, the compute unit should be deployed within seconds, e.g. immutable. prebaked container. You launch containers on demand, and pay by seconds.