Follow-up from student: What does anuloma veloma do that other pranayama techniques do not? For example, should one just be patient/content with spinal breathing for “as long as it takes?”
As far as whether anulom viloma pranayam is “best,” I would not look at it that way. In yoga practice of this sort, there really is no “best,” only what is appropriate for your practice today. Spinal breathing will eventually lead you to want to add other practices to your pranayama. This will happen spontaneously and automatically. There is no timetable and no one is keeping score. Remember, the successful practice of yoga is measured in years and decades, not weeks or months. It may be that spinal breathing is sufficient for many years of practice. If your practice is both steady and regular, at some point you will be drawn to add to it. You will know when the time is right, and if you are not sure, it is easy enough to experiment for a bit so you can assess your readiness better.
Anulom Viloma is a more forceful and powerful pranayama practice than spinal breathing. In anulom viloma you are actually directing the prana into the subtle nerve channels by switching the breath from nostril to nostril and by adding the kumbhaka phase. This purifies the nadis more directly than spinal breathing, but both work towards the same end. If your anuloma viloma practice is gratifying to you, but you are running short of time, we would have no problem with cutting back on some of the time spent in meditation and spinal breathing so that you can fit it in.