Plesk 18.0.54, published July 18th, 2023:
Added the ability to schedule hourly backups in Backup Manager. To enable the feature, add the following lines to the panel.ini file:
[pmm]
allowHourlyTask = on
By default, the ability to schedule hourly backups is only enabled for Plesk administrators. To enable resellers and customers to do so as well, go to Tools & Settings > Backup Manager, click Settings > select the “Allow customer and reseller accounts to schedule hourly backups” checkbox, and then click OK.