If it's any help, I did an SQL query that pulls in all courses, and then if the blocks.id and blocks.blockname are null then that course needs to have the block added (the left join takes care of that)
SELECT DISTINCT course.id, course.shortname, course.fullname, blocks.id , blocks.blockname, blocks.parentcontextid FROM database_name_here.mdl_course as course inner join moodle_2015.mdl_context as context on context.instanceid = course.id left join moodle_2015.mdl_block_instances as blocks on blocks.blockname = "choose_name_of_block" AND context.id = blocks.parentcontextid ;
Note this is pure SQL, if using Moodle to query it will be slightly different
Just update the database name and the name of the block to get the results