In the Yoga Practice related to meditation, the practice is supposed to be done for a prolonged time, without breaks, and with respectful attitude…. Yoga Sutras of Patanjali.
How about other Yoga practices, such as exercise, breathing, chanting, etc.?
Actually, all the practices require mind as the prime force to start. Some of them use body in addition to the mind. However, when a practice is done, it is recorded in the mind. And, that recording is available for the later usage. When the recording is repeated frequently, it really forms an impression (called Sanskara, in terminology of Meditation). The impression drives the later actions of that person.
However, the impression has to be strong enough for this to happen. Therefore, one should patiently continue their practice until the impression becomes very strong. In other words, one should become established in their practice.
This is also the basis of repetition of Mantra a particular number of times. However, that repetition has to be sincere. Otherwise, it has to be done for longer time.