The ratios might work for you. However, what’s most important is your comfort, relaxation, concentration, and prayer. It is better and simpler to listen to your body. The purpose of the ratios, though, is to have a deep retention, before moving towards a relaxed exhalation. You must gauge your body, lungs, and needs as you practice. Relaxation and retention, again, is most important, which is why Swami Sivananda provided the ratios as he did. But again, you must listen to your body and comfort zone.