In the teens especially, the program changed almost every day...

Regent Theatre, Albany, New York - September 24, 1917

In the 1920s, second-run theaters were pretty much the same, changing every two days or so.
Keystone Theatre, New York City, New York - May 4, 1925

Bigger theaters would show a film for 3-4 days, especially early in the film's run.
Loew's Greeley Square, New York - October 18th, 1926

The really big theaters in New York and Los Angeles would show the same film all week. This program starts on Sunday.
Strand Theatre, New York City, New York - November 14, 1915

And this showcase theater in Philadelphia starts their weekly program on Monday.
Loew's Aldine Theatre, Philadelphia, Pennsylvania - March 9, 1925

In the 1930s, the same still applied. Smaller theaters or second-run theaters changed every two days or so.
Lyric Theatre, Rochester, New York - October 19, 1930

While big first-run theaters showed the same film all week.
Strand Theatre, New York City, New York - October 14, 1938