An AWS account comes with certain limits that can be found in the AWS console:
These are meant to protect the customer as well as the provider against any unintentional use. The following are examples:
A coding error in your CloudFormation template, resulting in an unexpected amount of storage or other resources being provisioned
A misconfigured Auto Scaling Group, launching tens or hundreds of instances
Your user making an API call to request an unusual number of instances
As we can see, the said limits are an overall good idea, most of the time.
If you find yourself in a production environment, getting ready for a major event and the traffic spike that comes with it, you certainly want to be aware of your current AWS service limits. Most instance types are initially limited to 20, VPC EIPs to 5, and storage types to 20 TB.
Ideally, you would review these as soon as you get an idea of your expected usage baseline (allowing for bursting) and contact AWS Support...