AWS Backup - is hourly backups an effective approach

There is no performance impact to the resource being backed up using AWS Backup. Resource performance during backup window depends on the underlying storage and its utilization during that time. AWS Backup supports continuous backups and point-in-time recovery (PITR) in addition to snapshot backups. With continuous backups, you can restore your AWS Backup-supported resource by rewinding it back to a specific time that you choose, within 1 second of precision (going back a maximum of 35 days). Compare that with snapshot backups, which you can only take as frequently as every hour. Continuous backup works by first creating a full backup of your resource, and then constantly backing up your resource’s transaction logs. There has been no performance impact reported when using continuous backup for RDS. For more details on continuous backup refer to below article,

https://docs.aws.amazon.com/aws-backup/latest/devguide/point-in-time-recovery.html

In general it is advised to schedule backup during off peak hours depending on the application/database usage of the underlying resource. With respect to hourly snapshot backup of RDS or EC2 performance impact are a rare occurrence. Performance impact can be caused when a high performing application/database is run on a ec2 or RDS resource where the underlying resource configuration does not meet the application/database performance requirement.

AWS backup (EBS) is about creating temporary snapshot and backup the data from it. There is performance penalty during snapshot creation but it can be negligible or not noticeable to your application, provided how busy or IO intensive is your application. For hourly backup, you need to weigh what is important, RPO or performance. For same reason, point 7 says that It is best to create backups during scheduled downtimes/maintenance windows when user impact is minimal.