You are able to do this Shabar mantra chanting for 11, 21, 31, or 41 days, the location and time of mantra chanting must be the exact same for the number of days you want to do sadhana. You may use Rudraksha or Tulsi rosary to chant the mantra. https://shabar27159.blogkoo.com/most-powerful-sarv-karya-sidh-shabar-mantra-karya-siddhi-shabar-mantra-most-powerful-shabar-mantra-no-further-a-mystery-51917009