You can create up to 5000 log groups per account.
You must use the following guidelines when naming a log group:
Log group names must be unique within a region for an AWS account.
Log group names can be between 1 and 512 characters long.
Log group names consist of the following characters: a-z, A-Z, 0-9, '_' (underscore), '-' (hyphen), '/' (forward slash), and '.' (period).