Two laws reign supreme in the training world:
1. The law of specificity
2. The law of individual differences
There is research to support countless methodologies. There is also research that contradicts other research.
You must test things out yourself at times. Follow in the footsteps of those who have walked a similar path.
Study, learn, DO THE WORK. The trenches are the laboratories. Enjoy the study and pursuit of knowledge. Love the application and testing more.