This plugin serves several purposes. It will save failed entries in the backlog, to make sure they can be retried even if they scroll out of your input. It also enforces an interval before retrying again, so that other possibly acceptable entries may be grabbed in place of the failing entry. Lastly, it rejects entries that have failed more than a certain number of times.
By default, there is a 1 hour wait time in between retries of failed entries. This will be increased by 1.5 times on each successive failure of the entry. By default, entries will be retried 3 times, (meaning 4 total failures are possible.)
CLI flexget failed provides tools to list and clear failed entries.
This plugin is a builtin and does not need to be explicitly placed in your task unless you would like to override the defaults.
retry_failed:
retry_time: 30 minutes # Base time in between retries
retry_time_multiplier: 2 # Amount retry time will be multiplied by after each successive failure
max_retries: 5 # Number of times the entry will be retried