The Jack Benny Program Guide
Collection #1 - The Jack Benny Radio Program (1932-1955)
1932-05 to 1932-11 - Canada Dry - NBC
1932-11 to 1933-02 - Canada Dry - CBS
1933-03 to 1933-06 - Chevrolet Program - NBC
1933-10 to 1934-04 - Chevrolet Program - NBC
1934-04 to 1934-09 - General Tire Program - NBC
1934-   to 1942    - General Foods - Jell-O - NBC
1942-   to 1944    - General Foods - Grape Nuts - NBC
1944-   to 1948    - American Tobacco - Lucky Strike - NBC
1948-   to 1955    - American Tobacco - Lucky Strike - CBS


Question does changing network, but not sponsor constitute changing a season - it was done twice 
NBC Nov 1932 to CBS for canada dry
and again 1948 NBC to CBS for Lucky Strike - this was an actual "mid-season" change done at the end of the year



Typically contracts ran 13 weeks
so may 5, 1932 to july 28

Can Dry with olsen tan to October - 52 epi - 26weeks


Jack Benny Program
1932-05-02 -- 1932-10-26 - Season 1 - 26 weeks - Monday/Wednesday - NBC - Canada Dry - Ed Thorgersen, George Olsen, Ethel Shutta, Mary Livingston, Sam Hearn
1932-10-30 -- 1933-01-26 - Season 2 - 13 weeks - Sunday/Thursday  - CBS - Canada Dry - George Hicks, Ted Weems, Mary Livingstone, Sam Hearn, Sid Silvers
1933-03-03 -- 1933-06-23 - Season 3 - 17 weeks - Friday - NBC - Chevrolet - Howard Claney, Frank Black, Andrea Marsh, Mary Livingston, Sam Hearn
1933-10-01 -- 1934-04-01 - Season 4 - 26 weeks - Friday - NBC - Chevrolet - Howard Claney, Frank Black, Andrea Marsh, Mary Livingston, Sam Hearn
1934-04-06 -- 1934-09-28 - Season 5 - 26 Weeks - Friday - NBC - General Tire - Don Wilson, Don Bestor, Frank Parker, Mary Livingstone, Sam Hearn
1934-10-14 -- 1935-07-14 - Season 6 - 40 Weeks - Sunday - NBC - Jell-O - Don Wilson, Don Bestor, Frank Parker, Mary Livingstone, Sam Hearn
1935-09-25 -- 1936-06-21 - Season 7 - 39 Weeks - Sunday - NBC - Jell-O - Don Wilson, Johnny Green, Kenny Baker, Mary Livingstone, 
1936-10-04 -- 1957-06-27 - Season 8 - 39 Weeks - Sunday - NBC - Jell-O - Don Wilson