More than the time factor, it is important to repeat the action on the joints everyday. Like in Surya namaskar, the same actions are done quite a few times. The connective tissue around the joints learn to give in by repetition. Intensity is fine too, but repetition is more important. I have understood this after I started practicing the KYM style. In a week, I practice many styles that appeal to me. KYM, Vinyasa flow, Aṣtanga and my own style. When I practice the KYM style, I notice that my joints relax way more and I can go deeper into all the poses. KYM style is where a simple sequence is repeated about 6 times, coordinating the movements with the breath. The breath is never hurried, it is really slow long deep breaths. And, the bonus is that I always want to meditate at the end of the session, which does not happen with any other style. Meditating even for a  few minutes was always a challenge for me, it was an alien concept. But nowadays I am getting the hang of it.

It is not just the joints and the muscles that learn by repetition. Even the mind is supposed to learn only by repetition. The Surya namaskar mantra, gayatri and many other prayers associated with the Sun are chanted every day to greet the Sun and to purge the mistakes of the previous day. The yamas (Ahimsa, Satya, Asteya, Brahmacharya, Aparigraha) and niyamas (Saucha, Santosha, Tapas, Swadhyaya, Ishvarapranidhana) of Yoga are also to be practiced all the time and one can get to this only by repetition.

Shampoo. Rinse. Repeat. Good advice.

Then I ended up at KYM, where one can find the real explanation to all things Yoga. One of my teachers at KYM mentioned that Surya namaskar is a complete exercise. The namaskars have built in counter poses, forward bends and backward bends, flexions and extensions. When you do the Surya namaskars, you will work out the shoulders, spine, the hip joints, hamstrings, hands, chest, neck, ankles, toes and more. Downward facing dog is similar to an inversion in its benefits. If you just add in a few parivrtta trikonasana (revolved triangle) at the end, you have worked out most of your body. Pranayama is built into this sequence. Of course, it is a prayer to the Sun, who is the sustainer of life to enhance good health. This is a way to take in the radiance of the Sun inside you to energize and begin the day.

In the Vedic times, people used to recite mantras during the hold between an inhale and exhale, which would make the practice very deep. At KYM, I have practiced Surya namaskars having outsourced the mantra recitation to the teacher and it was a very beautiful experience. Namaskar itself is not done in a hurry; every inhale and exhale is long to go with the mantra. Each inhale could be 7 seconds or more in length. Just slowing down and concentrating on the powers of the Sun was a new way to practice.

The gayatri mantra is also a mantra of the Sun, among others. Strangely, Sun is portrayed as a woman. Gayatri, Savitri and Saraswati are the three names of the Sun. The morning sun is Gayatri, Savitri is the noon sun and and Saraswati is the setting sun.

Surya namaskars with or without mantras is a great sequence to practice when there is just 30 minutes of yoga time in a day. I can say for sure, practicing this in the morning is way better, as the body tends to remember for a few hours to breathe slow as you carry on with your daily life.