As it is a Swyama Siddha Hanuman Mantra it does not have being chanted for a fixed variety of Mantra Repetitions for having the ability to utilize it. Unique worship and rituals and rules with regards to way, sitting down mat, and counting rosary usually are not advisable for chanting https://www.youtube.com/watch?v=ufkmD95y7fE&t=32s