Clarification on backend billing

[Jacob R]

Just a quick question of clarification regarding backend instances when using services. The documentation states that:

"Note: For each instance, there is an initial start up cost of 15 minutes instance time."

This to me implies if you have a single 1 second request going to a backend instance, you start with 15 minutes billed. Then the documentation states

"Billing begins when an instance starts and ends fifteen minutes after a manual instance shuts down or fifteen minutes after a basic instance has finished processing its last request."

This suggests that after the 1 second request completes, there will be at least 15 minutes billed after that. So the total billing for a 1 second request to a backend instance would be 30 minutes, is that correct?

Secondly, just say that 1 second request completed and the instance shuts down 60 seconds later. Then you do another 1 second request. Would this result in another 30 minutes billed?  So the total to handle two 1 second requests 1 minute apart would be 60 minutes billed? I am trying to work out the economics of this. I assume this is not the case, what am I missing?

Thanks!

Jacob