I understand that reserved instances in AWS are more of a billing thing rather actual instances - they're not attached to an actual instance - and I wonder:
If I buy a reserved instance of a specific time in a specific region and availability zone - will I be billed the same rate if I use a single instance 24 hours a day vs. running 24 instances (same size, same availability zone) for 1 hour (same hour, e.g. 00:00-01:00) every day?
Is there a difference in the types of reserved instances with regards to this question?
If the answer is no, and obviously the case is not such a clear cut (i.e. I have instances coming and going all the time - some work simultaneously and some on different times) - how can I make the calculation whether or not it makes sense for me to purchase reserved instances?