As I.K. Taimni notes:
“It need hardly be pointed out that Yoga is an experimental science and as in all sciences new techniques are being constantly discovered by individual teachers and taught to their disciples. Thus, each advanced teacher, though he follows the broad principles of Yoga and techniques of his particular school, imparts a personal touch to his teachings by introducing certain minor practices of his own. These are generally continued in a more or less modified form as long as the school lasts. But in most cases such schools quickly degenerate into mere academic bodies carrying on a dead tradition”.
Taimni IK. The Science of Yoga p.20.
Here we see that the methods and techniques are changeable across the different lineages and they adapt to time and place to carry the essence of the subject.
etc.
etc.
etc.