It's typically fine - AWS bills by GB/s (in ms), not by number of functions in an account.
There are limits to the number of functions per account, and number of resources per CloudFormation stack (etc); but within those parameters it's usually a good idea to use one function for a specific controller or action. This allows you to limit IAM permissions, configure memory/CPU, and define associated resources at a per-controller level.
There are limits to the number of functions per account, and number of resources per CloudFormation stack (etc); but within those parameters it's usually a good idea to use one function for a specific controller or action. This allows you to limit IAM permissions, configure memory/CPU, and define associated resources at a per-controller level.