The Ashtanga practice is an energitic practice, fueled by the breath. Movements are done to the breath. The inhale and the exhale of each breath should be the same length. One complete breath to the next can be a different length but the two parts of one breath should be the same length.
In the sun salutes you should put your hands flat to the floor even if you have to bend your knees to get them there. If you have finger tips only touching the floor then you are taking and extra half breath to get the hands flat to the floor so you can jump back. The half breath is not in the sequence. It is better to get your hands flat to the floor at the start of the sun salute.
When jumping back the more advanced practice is land with the elbows bent in low plank rather than jumping back in high plank and lowering down.
If you find yourself running out of breath during the sun salutes it is best to take a little sip of breath rather than holding the breath until you complete the movement.
To protect the knees you should do 5 A and 3 B rather than 5 of each.
The primary and intermediate series can be divided into pieces in several ways.
You can alternate doing primary one day, intermediate the next. And when you learn advanced you can add that into the alternating cycle as well.
Also you can do the first half of primary and the first half of intermediate.
Another option is to the full primary series and then the last half of intermediate.
