If a lead meets the conditions set up in this automation record (i.e yards, users, source etc) once if hits the trigger it will automatically reallocate the lead to a new user (who will receive a new lead allocation notification).  With this setting it's now possible to remove leads from users who are not doing anything with them, and reassign to make sure your customers are getting the required level of service.  Actions are not available on every Automation trigger, with the following triggers allowing for the 'Reallocate Lead' action.

As you can see from the types of triggers it is available for, the 'Reallocate Lead' function should only be used to reallocate only the leads that are getting severely neglected by the sales team.  When setting up the Automation record you need to select the 'Reallocate Lead' action, set the timeframe after the trigger hits that you want it to reallocate (i.e 1 hour after the lead becomes Stalled) and the user you want to reallocate the lead to.  Leads can only be reallocated to one user and they can be a manager, or non-manager.

As there could be multiple managers in the Manage Leads role it is required for you to specify the recipient of the reallocated leads.  The best approach to setting up this automation setting is to add Yard and User groupings to the Automation filters, and select the manager who looks after that yard/user grouping.