There is no fixed number of reciters. Aakhand Path is believed to have its origin in the middle of the eighteenth century.During the days of persecution. the Sikhs had to remain prepared to move from one place to another, at a very short notice; hence they had to complete the reading of the Scriptures in a short time.
In the second half of the twentieth century it became a fashion to perform this ceremony. Ideologically speaking. Aakhand Path is not in consonance with the Sikh fundamentals as Sikhs must not read the Scriptures simply as a ritual. A Sikh must read, understand and try to live his life according to the Scriptures.
References :
1. The Sikh Reference Book; Dr Harjinder Singh Dilgeer