CREATE TABLE table_1251 ("No. in series" CLOB, "No. Disc" FLOAT, "Title" CLOB, "Directed by" CLOB, "Written by" CLOB, "Original air date" CLOB, "Length  ( minutes ) " FLOAT)

Name the maximum number of disc for bill gereghty
SELECT MAX("No. Disc") FROM table_1251 WHERE "Directed by" = 'Bill Gereghty'
SELECT MAX("No. Disc") FROM "table_1251" WHERE "Directed by" = 'Bill Gereghty'