I know that Olympic sprinters change up their routine every year.. this is because they are so advanced that they perform better on some training, yet can not get consistent gains without mixing it up.. it’s all highlighted in the science and practice of strength training
for us mortals though, I do not think I should ever change my workout.. consistency is something I fail to do and so do many other people..boredom is another reason why I think people mix it up
only for pro’s should this take effect in my experience