Who was associated with the decision to hold the National Convention every two years?

The decision to hold the National Convention every two years is closely associated with Ethel Lamay Calimese. She played a significant role in the organization, particularly in the planning and structuring of Delta Sigma Theta's conventions. Her leadership and vision helped to establish a regular schedule for the National Convention, which was crucial for maintaining engagement and continuity among members. This biannual occurrence allows for the continuation of the organization’s mission, community service, and the sharing of ideas among members, enhancing the overall functioning of Delta Sigma Theta Sorority, Inc.

While the other individuals mentioned made important contributions to the sorority, Ethel Lamay Calimese is best recognized for this specific decision and its impact on the organization's governance and cohesion.