According to best practices, the average duration of a Scrum sprint should be:

One to five weeks is too broad and extends beyond the Scrum Guide's defined maximum of one month in some interpretations and overlaps incorrectly with the standard range.

The Scrum Guide specifies that a Sprint is a fixed-length event of one month or less, and the recognized best practice range is two to four weeks. This duration is long enough to deliver a meaningful increment while remaining short enough to enable frequent inspection, adaptation, and course correction.

Two to four months far exceeds the Scrum Guide's one-month maximum and eliminates the rapid feedback loop that Scrum is designed to provide.

One to five months is not a valid sprint duration under the Scrum Guide or any recognized agile best practice framework.