The Soviet Union celebrates International Labor Day on May 1 and October Revolution anniversary on November 7. As the National Security Archives of George Washington University pointed out, Although the largest parade was held in Moscow, other Soviet cities also held parades. Moscow sometimes holds an air show in July, focusing on fighter planes.
As soon as they flew out of sight of the parade ground, the 10 Buffalo Bombers turned around and re-flew the same route six times. As a result, US intelligence mistakenly believed that the Soviets had dispatched 60 bombers instead of 10, which meant that Moscow had as many as 600 Buffalo strategic bombers, much more than the West had previously thought. This raised concerns about the bomber gap in the United States, fearing that the Soviets would soon overtake the United States in the production of long-range bombers, and that President Eisenhowers approval ratings would suffer. He has blackened the pot for this nonexistent gap. In fact, the Soviets had only 23 Buffalo bombers.
Source: Responsible Editor of Reference Message Network: Zou Yuan_NBJS7274