We are using SharePoint 2013 and have task of creating timer jobs which run everyday, with functionality like sending out emails based on due dates of list items, adding items to list, changing values of list items.
I am interested to know the basis on which we should make the decision whether to set the scope of timer job feature to web/sitecol/webapp/farm?
As a TimerJob has to be associated with either a WebApplication or Service, the most scope of the feature would be common would be either WebApplication or Farm.
But as always with scoping features the main concern should be at what scope does it make sense for be able to enable/disable this functionality from a business perspective. This might mean that the right scope is Web as you might want to target individual sites in your timer job. That would then imply that the feature on activation should check if the TimerJob is already present for the WebApp and if not add it and on deactivation check if this is the last site and if so remove the timerjob.
