Samael Aun Weor wrote this section based upon the investigations of other writers. Upon further investigation of his own, he later wrote "I regretfully have to disagree with the opinion of the Master Huiracocha about the Tattvic day-timer. In his Tattvameter he states that the five Tattvas successively vibrate for two hour periods, and that each Tattva vibrates for twenty-four minutes... Yet, this is in discordance with the facts and observations. Therefore, the best Tattvic day-timer is the one from Nature." He then explains that one should observe the local conditions to determine the dominate tattvic forces. You can learn more about this in Esoteric Medicine and Practical Magic, in the section about Ens Espirituale.

Counting to twenty is just a guideline to help us extend the inhalation and exhalation. If you cannot reach twenty that is ok. The counting is not required, whether for the inhalation, holding the breath, or the exhalation. What is required are relaxation, concentration, and imagination.