As this is a Swyama Siddha Hanuman Mantra it doesn't have for being chanted for a fixed quantity of Mantra Repetitions for being able to use it. Exclusive worship and rituals and guidelines relating to way, sitting mat, and counting rosary usually are not advised for chanting this Hanuman Mantra. https://www.youtube.com/watch?v=ufkmD95y7fE&t=32s