You can do it any way you please. The important thing is that you do it. If you have a short period of time, however, you will probably experience more results by doing just one of the exercises.
Remember, you can practice Qigong anytime. When at a stop light, visualize the energy column in your torso, or move the energy through the Small Universe, or focus breathing in your lower Dantian, or breathing in energy and breathing out blockages and excess energy.
Chunyi says all day can be a Qigong practice. Most of the times I am typing here on the Forum I'm breathing into my lower Dantian.
